thermodynamics (17nov23)

git-svn-id: svn://tug.org/texlive/trunk@68881 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 1398 insertions, 858 deletions

diff --git a/Master/texmf-dist/tex/latex/thermodynamics/thermodynamics.sty b/Master/texmf-dist/tex/latex/thermodynamics/thermodynamics.sty
index 5d121549971..10036eb2021 100644
--- a/Master/texmf-dist/tex/latex/thermodynamics/thermodynamics.sty
+++ b/Master/texmf-dist/tex/latex/thermodynamics/thermodynamics.sty
@@ -8,7 +8,7 @@
 %% 
 %% This is a generated file.
 %% 
-%% Copyright (C) 2017-2018 by Karl D. Hammond
+%% Copyright (C) 2022-2023 by Karl D. Hammond
 %% 
 %% Karl D. Hammond,
 %% Department of Chemical Engineering
@@ -23,983 +23,1523 @@
 %% and version 1.3 or later is part of all distributions of LaTeX
 %% version 2005/12/01 or later.
 \NeedsTeXFormat{LaTeX2e}
+\RequirePackage{expl3}
 \ProvidesPackage{thermodynamics}
-    [2022/04/29 v1.00 thermodynamics package]
+    [2023/11/16 v2.00 thermodynamics notation]
+%%^^A            = C_i \gammamol_i \Henrymol_i
+\ExplSyntaxOn
+\cs_generate_variant:Nn \tl_if_eq:nnTF { xxTF }
 \RequirePackage{amstext}
 \AtBeginDocument{
     \@ifpackageloaded{pxfonts}{%
-        \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-10mu d}}%
+        \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-10mu d}
     }{}
     \@ifpackageloaded{newpxmath}{%
-        \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-10mu d}}%
+        \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-10mu d}
     }{}
     \@ifpackageloaded{txfonts}{%
-        \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-11mu d}}%
+        \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-11mu d}
     }{}
     \@ifpackageloaded{mathptmx}{%
-        \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-10mu d}}%
+        \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-10mu d}
     }{}
     \@ifpackageloaded{newtxmath}{%
-        \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-12mu d}}%
+        \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-11mu d}
     }{}
     \@ifpackageloaded{mathdesign}{%
-        \def\@charter{mdbch}%
-        \def\@utopia{mdput}%
-        \def\@garamond{mdugm}%
-        \ifx\MD@default@family\@utopia
-            \providecommand*{\dbar}{{\mkern8mu\mathchar'26\mkern-20mu d}}%
-        \fi
-        \ifx\MD@default@family\@charter
-            \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-15mu d}}%
-        \fi
-        \ifx\MD@default@family\@garamond
-            \providecommand*{\dbar}{{\mkern5mu\mathchar'26\mkern-17mu d}}%
-        \fi
+        \tl_const:Nn \c__thermodynamics_charter_tl {mdbch}
+        \tl_const:Nn \c__thermodynamics_utopia_tl {mdput}
+        \tl_const:Nn \c__thermodynamics_garamond_tl {mdugm}
+        \tl_if_eq:NNT \MD@default@family \c__thermodynamics_utopia_tl
+        { \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-20mu d}
+        }
+        \tl_if_eq:NNT \MD@default@family \c__thermodynamics_charter_tl
+        { \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-15mu d}
+        }
+        \tl_if_eq:NNT \MD@default@family \c__thermodynamics_garamond_tl
+        { \ProvideDocumentCommand{\dbar}{}
+            {\mkern5mu\mathchar'26\mkern-17mu d}
+        }
     }{}
     % Defaults to Computer Modern
-    \providecommand*{\dbar}{{\mkern3mu\mathchar'26\mkern-12mu d}}
-}
-\newcommand*{\totalenergy@symbol}{E}
-\newcommand*{\internalenergy@symbol}{U}
-\newcommand*{\Helmholtz@symbol}{A}
-\newcommand*{\Gibbs@symbol}{G}
-\newcommand*{\Landau@symbol}{\Omega}
-\newcommand*{\enthalpy@symbol}{H}
-\newcommand*{\entropy@symbol}{S}
-\newcommand*{\area@symbol}{a}
-\newcommand*{\volume@symbol}{V}
-\newcommand*{\mole@symbol}{n}
-\newcommand*{\heat@symbol}{Q}
-\newcommand*{\work@symbol}{W}
-\newcommand*{\temperature@symbol}{T}
-\newcommand*{\pressure@symbol}{P}
-\newcommand*{\thermo@underline}[1]{%
-  \mkern1mu\underline{\mkern-1mu #1\mkern-4mu}\mkern4mu%
-}
-\newcommand*{\thermo@overline}[1]{%
-  \mkern2mu\overline{\mkern-2mu #1\mkern-1mu}\mkern1mu%
-}
-\newcommand*{\PartialOpen}{(}
-\newcommand*{\PartialClose}{)}
-\newcommand*{\PartialEmptyClose}{)}
+    \ProvideDocumentCommand{\dbar}{}
+        {\mkern3mu\mathchar'26\mkern-12mu d}
+}
+\tl_new:N \g__thermodynamics_total_energy_symbol
+\tl_new:N \g__thermodynamics_internal_energy_symbol
+\tl_new:N \g__thermodynamics_Helmholtz_symbol
+\tl_new:N \g__thermodynamics_Gibbs_symbol
+\tl_new:N \g__thermodynamics_Landau_symbol
+\tl_new:N \g__thermodynamics_enthalpy_symbol
+\tl_new:N \g__thermodynamics_entropy_symbol
+\tl_new:N \g__thermodynamics_area_symbol
+\tl_new:N \g__thermodynamics_volume_symbol
+\tl_new:N \g__thermodynamics_mole_symbol
+\tl_new:N \g__thermodynamics_heat_symbol
+\tl_new:N \g__thermodynamics_work_symbol
+\tl_new:N \g__thermodynamics_temperature_symbol
+\tl_new:N \g__thermodynamics_pressure_symbol
+
+\tl_gset:Nn \g__thermodynamics_total_energy_symbol E
+\tl_gset:Nn \g__thermodynamics_internal_energy_symbol U
+\tl_gset:Nn \g__thermodynamics_Helmholtz_symbol A
+\tl_gset:Nn \g__thermodynamics_Gibbs_symbol G
+\tl_gset:Nn \g__thermodynamics_Landau_symbol \Omega
+\tl_gset:Nn \g__thermodynamics_enthalpy_symbol H
+\tl_gset:Nn \g__thermodynamics_entropy_symbol S
+\tl_gset:Nn \g__thermodynamics_area_symbol a
+\tl_gset:Nn \g__thermodynamics_volume_symbol V
+\tl_gset:Nn \g__thermodynamics_mole_symbol n
+\tl_gset:Nn \g__thermodynamics_heat_symbol Q
+\tl_gset:Nn \g__thermodynamics_work_symbol W
+\tl_gset:Nn \g__thermodynamics_temperature_symbol T
+\tl_gset:Nn \g__thermodynamics_pressure_symbol P
+\cs_new:Nn \__thermodynamics_underline:n
+{ \mkern1mu\underline{\mkern-1mu #1\mkern-4mu}\mkern4mu }
+\cs_new:Nn \__thermodynamics_overline:n
+{ \mkern2mu\overline{\mkern-2mu #1\mkern-1mu}\mkern1mu }
+\tl_new:N \l__thermodynamics_PartialOpen_tl
+\tl_new:N \l__thermodynamics_PartialEmptyClose_tl
+\tl_new:N \l__thermodynamics_PartialClose_tl
+
+\tl_set:Nn \l__thermodynamics_PartialOpen_tl {(}
+\tl_set:Nn \l__thermodynamics_PartialClose_tl {)}
+\tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {)}
 \DeclareOption{EUAGHan}{}% the default
-\DeclareOption{EUAGHaN}{\renewcommand*{\mole@symbol}{N}}%
+\DeclareOption{EUAGHaN}{\tl_gset:Nn \g__thermodynamics_mole_symbol N}%
 \DeclareOption{EUHAGan}{\ExecuteOptions{EUAGHan}}
 \DeclareOption{EUHAGaN}{\ExecuteOptions{EUAGHaN}}
-\DeclareOption{EUFGHAn}{% this is my favorite set of symbols
-  \renewcommand*{\Helmholtz@symbol}{F}%
-  \renewcommand*{\area@symbol}{A}%
-}
-\DeclareOption{EUFGHAN}{% this is my second favorite set of symbols
-  \renewcommand*{\Helmholtz@symbol}{F}%
-  \renewcommand*{\area@symbol}{A}%
-  \renewcommand*{\mole@symbol}{N}%
-}
-\DeclareOption{EEFGHAn}{% this treats all energy the same way(?)
-  \renewcommand*{\internalenergy@symbol}{E}%
-  \renewcommand*{\Helmholtz@symbol}{F}%
-  \renewcommand*{\area@symbol}{A}%
-}
-\DeclareOption{EEFGHAN}{% this treats all energy the same way(?)
-  \renewcommand*{\internalenergy@symbol}{E}%
-  \renewcommand*{\Helmholtz@symbol}{F}%
-  \renewcommand*{\area@symbol}{A}%
-  \renewcommand*{\mole@symbol}{N}%
+\DeclareOption{EUFGHAn}{%
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
+  \tl_gset:Nn \g__thermodynamics_area_symbol A
+}
+\DeclareOption{EUFGHAN}{%
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
+  \tl_gset:Nn \g__thermodynamics_area_symbol A
+  \tl_gset:Nn \g__thermodynamics_mole_symbol N
+}
+\DeclareOption{EEFGHAn}{%
+  \tl_gset:Nn \g__thermodynamics_total_energy_symbol {\mathcal{E}}
+  \tl_gset:Nn \g__thermodynamics_internal_energy_symbol E
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
+  \tl_gset:Nn \g__thermodynamics_area_symbol A
+}
+\DeclareOption{EEFGHAN}{%
+  \tl_gset:Nn \g__thermodynamics_total_energy_symbol {\mathcal{E}}
+  \tl_gset:Nn \g__thermodynamics_internal_energy_symbol E
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
+  \tl_gset:Nn \g__thermodynamics_area_symbol A
+  \tl_gset:Nn \g__thermodynamics_mole_symbol N
 }
 \DeclareOption{EEFGHan}{%
-  \renewcommand*{\internalenergy@symbol}{E}%
-  \renewcommand*{\Helmholtz@symbol}{F}
+  \tl_gset:Nn \g__thermodynamics_total_energy_symbol {\mathcal{E}}
+  \tl_gset:Nn \g__thermodynamics_internal_energy_symbol E
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
 }
 \DeclareOption{EEFGHaN}{%
-  \renewcommand*{\internalenergy@symbol}{E}%
-  \renewcommand*{\Helmholtz@symbol}{F}
-  \renewcommand*{\mole@symbol}{N}%
+  \tl_gset:Nn \g__thermodynamics_total_energy_symbol {\mathcal{E}}
+  \tl_gset:Nn \g__thermodynamics_internal_energy_symbol E
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
+  \tl_gset:Nn \g__thermodynamics_mole_symbol N
 }
 \DeclareOption{EEAGHan}{%
-  \renewcommand*{\internalenergy@symbol}{E}%
+  \tl_gset:Nn \g__thermodynamics_total_energy_symbol {\mathcal{E}}
+  \tl_gset:Nn \g__thermodynamics_internal_energy_symbol E
 }
 \DeclareOption{EEAGHaN}{%
-  \renewcommand*{\internalenergy@symbol}{E}%
-  \renewcommand*{\mole@symbol}{N}%
+  \tl_gset:Nn \g__thermodynamics_total_energy_symbol {\mathcal{E}}
+  \tl_gset:Nn \g__thermodynamics_internal_energy_symbol E
+  \tl_gset:Nn \g__thermodynamics_mole_symbol N
 }
-\DeclareOption{EUAGHAn}{% Helmholtz free energy and area look the same here
-  \renewcommand*{\area@symbol}{A}%
+\DeclareOption{EUAGHAn}{%
+  \tl_gset:Nn \g__thermodynamics_area_symbol {\mathcal{A}}
 }
-\DeclareOption{EUAGHAN}{% Helmholtz free energy and area look the same here
-  \renewcommand*{\area@symbol}{A}%
-  \renewcommand*{\mole@symbol}{N}%
+\DeclareOption{EUAGHAN}{%
+  \tl_gset:Nn \g__thermodynamics_area_symbol {\mathcal{A}}
+  \tl_gset:Nn \g__thermodynamics_mole_symbol N
 }
 \DeclareOption{EUFGHan}{%
-  \renewcommand*{\Helmholtz@symbol}{F}%
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
 }
 \DeclareOption{EUFGHaN}{%
-  \renewcommand*{\Helmholtz@symbol}{F}%
-  \renewcommand*{\mole@symbol}{N}%
+  \tl_gset:Nn \g__thermodynamics_Helmholtz_symbol F
+  \tl_gset:Nn \g__thermodynamics_mole_symbol N
 }
-\DeclareOption{delta}{\let\dbar\delta}
-\let\@extensive\relax
-\let\@intensive\relax
-\let\@specific\hat
-\DeclareOption{extensive-plain}{%
-    \let\@extensive\relax
-    \let\@intensive\thermo@underline
+\DeclareOption{delta}{ \cs_set_eq:NN \dbar \delta }
+\cs_new:Nn \__thermodynamics_extensive:n {#1}
+\cs_new:Nn \__thermodynamics_intensive:n {#1}
+\cs_new:Nn \__thermodynamics_specific:n {\hat{#1}}
+
+\cs_new:Npn \__thermodynamics_set_intensive_plain
+{
+  \cs_set:Nn \__thermodynamics_extensive:n {\__thermodynamics_underline:n{##1}}
+  \cs_set:Nn \__thermodynamics_intensive:n {##1}
 }
-\DeclareOption{intensive-plain}{% the default
-    \let\@extensive\thermo@underline
-    \let\@intensive\relax
+\cs_new:Npn \__thermodynamics_set_extensive_plain
+{
+  \cs_set:Nn \__thermodynamics_extensive:n {##1}
+  \cs_set:Nn \__thermodynamics_intensive:n {\__thermodynamics_underline:n{##1}}
 }
+\cs_new:Npn \__thermodynamics_set_lowercase_pms
+{
+  \RenewDocumentCommand{\partialmolar}{m}
+  {
+    \tl_set:Nn \l__thermodynamics_pm_symbol_tl {\text_lowercase:n {##1}}
+    \__thermodynamics_generic_pm:
+  }
+}
+\cs_new:Npn \__thermodynamics_set_intensive_lowercase
+{
+  \cs_set:Nn \__thermodynamics_extensive:n {\text_uppercase:n {##1}}
+  \cs_set:Nn \__thermodynamics_intensive:n {\text_lowercase:n {##1}}
+  \cs_set:Nn \__thermodynamics_specific:n {\hat{\text_lowercase:n {##1}}}
+}
+\cs_new:Npn \__thermodynamics_set_extensive_superscripts
+{
+  \cs_set:Nn \__thermodynamics_extensive:n {{##1}\c_math_superscript_token t}
+  \cs_set:Nn \__thermodynamics_intensive:n {##1}
+}
+\DeclareOption{extensive-plain}{\__thermodynamics_set_extensive_plain}
+\DeclareOption{intensive-plain}{\__thermodynamics_set_intensive_plain} % the default
 \DeclareOption{intensive-lowercase}{% PLEASE don't use this!
-    \let\@extensive\MakeUppercase
-    \let\@intensive\MakeLowercase
-    \def\@specific#1{\MakeLowercase{\hat #1}}
-    \AtEndOfPackage{
-        \renewcommand*{\partialmolar}[1]{%
-            \gdef\pm@symbol{\MakeLowercase #1}\generic@pm}
-        \renewcommand*{\heatcapacitysymbol}{c}
-    }
+  \__thermodynamics_set_intensive_lowercase
+  \AtEndOfPackage{
+    \__thermodynamics_set_lowercase_pms
+    \RenewDocumentCommand{\heatcapacitysymbol}{}{c}
+  }
 }
 \DeclareOption{extensive-superscript}{%
-    \gdef\@extensive#1{{#1}^t}%
-    \let\@intensive\relax%
-    \AtEndOfPackage{%
-      \renewcommand*{\URt}{\internalenergy@symbol^{\residual,t}}
-      \renewcommand*{\HRt}{\enthalpy@symbol^{\residual,t}}
-      \renewcommand*{\FRt}{\Helmholtz@symbol^{\residual,t}}
-      \renewcommand*{\GRt}{\Gibbs@symbol^{\residual,t}}
-      \renewcommand*{\VRt}{\volume@symbol^{\residual,t}}
-      \renewcommand*{\SRt}{\entropy@symbol^{\residual,t}}
-      \renewcommand*{\UEt}{\internalenergy@symbol^{\excess,t}}
-      \renewcommand*{\HEt}{\enthalpy@symbol^{\excess,t}}
-      \renewcommand*{\FEt}{\Helmholtz@symbol^{\excess,t}}
-      \renewcommand*{\GEt}{\Gibbs@symbol^{\excess,t}}
-      \renewcommand*{\VEt}{\volume@symbol^{\excess,t}}
-      \renewcommand*{\SEt}{\entropy@symbol^{\excess,t}}
-    }
-}
-\newif\if@subscripted
-\@subscriptedtrue
-\DeclareOption{subscripts}{\@subscriptedtrue}
-\DeclareOption{nosubscripts}{\@subscriptedfalse}
+  \__thermodynamics_set_extensive_superscripts
+  \AtEndOfPackage{%
+    \RenewDocumentCommand{\URt}{}{\g__thermodynamics_internal_energy_symbol
+      \c_math_superscript_token{\residual,t}}
+    \RenewDocumentCommand{\HRt}{}{\g__thermodynamics_enthalpy_symbol
+      \c_math_superscript_token{\residual,t}}
+    \RenewDocumentCommand{\FRt}{}{\g__thermodynamics_Helmoholtz_symbol
+      \c_math_superscript_token{\residual,t}}
+    \RenewDocumentCommand{\GRt}{}{\g__thermodynamics_Gibbs_symbol
+      \c_math_superscript_token{\residual,t}}
+    \RenewDocumentCommand{\VRt}{}{\g__thermodynamics_volume_symbol
+      \c_math_superscript_token{\residual,t}}
+    \RenewDocumentCommand{\SRt}{}{\g__thermodynamics_entropy_symbol
+      \c_math_superscript_token{\residual,t}}
+    \RenewDocumentCommand{\UEt}{}{\g__thermodynamics_internal_energy_symbol
+      \c_math_superscript_token{\excess,t}}
+    \RenewDocumentCommand{\HEt}{}{\g__thermodynamics_enthalpy_symbol
+      \c_math_superscript_token{\excess,t}}
+    \RenewDocumentCommand{\FEt}{}{\g__thermodynamics_Helmoholtz_symbol
+      \c_math_superscript_token{\excess,t}}
+    \RenewDocumentCommand{\GEt}{}{\g__thermodynamics_Gibbs_symbol
+      \c_math_superscript_token{\excess,t}}
+    \RenewDocumentCommand{\VEt}{}{\g__thermodynamics_volume_symbol
+      \c_math_superscript_token{\excess,t}}
+    \RenewDocumentCommand{\SEt}{}{\g__thermodynamics_entropy_symbol
+      \c_math_superscript_token{\excess,t}}
+  }
+}
+%%^^A \[ \left(\frac{\partial U}{\partial S}\right)_V \quad\text{versus}\quad
+%%^^A    \left(\frac{\partial U(S,V)}{\partial S}\right) \]
+\bool_new:N \l__thermodynamics_subscripted_bool
+\bool_set_true:N \l__thermodynamics_subscripted_bool
+\DeclareOption{subscripts}{\bool_set_true:N \l__thermodynamics_subscripted_bool}
+\DeclareOption{nosubscripts}{\bool_set_false:N \l__thermodynamics_subscripted_bool}
 \DeclareOption{parentheses}{}
 \DeclareOption{brackets}{%
-  \renewcommand*{\PartialOpen}{[}%
-  \renewcommand*{\PartialClose}{]}%
-  \renewcommand*{\PartialEmptyClose}{]}%
+  \tl_set:Nn \l__thermodynamics_PartialOpen_tl {[}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {]}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {]}
 }
 \DeclareOption{braces}{%
-  \renewcommand*{\PartialOpen}{\{}%
-  \renewcommand*{\PartialClose}{\}}%
-  \renewcommand*{\PartialEmptyClose}{\}}%
+  \tl_set:Nn \l__thermodynamics_PartialOpen_t1 {\{}
+  \tl_set:Nn \l__thermodynamics_PartialClose_t1 {\}}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {\}}
 }
 \DeclareOption{bar}{%
-  \renewcommand*{\PartialOpen}{.}%
-  \renewcommand*{\PartialClose}{\rvert}%
-  \renewcommand*{\PartialEmptyClose}{.}%
+  \tl_set:Nn \l__thermodynamics_PartialOpen_tl {.}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {\rvert}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {.}
 }
 \DeclareOption{plain-derivatives}{% This implies dU(S,V,N)/dS notation
-  \renewcommand*{\PartialOpen}{.}%
-  \renewcommand*{\PartialClose}{.}%
-  \renewcommand*{\PartialEmptyClose}{.}%
-  \ExecuteOptions{nosubscripts}%
-}
-\newcommand*{\ncomponents}{C}
-\newcommand*{\allNs}{\allcomponents{\Nt}}
-\newcommand*{\allXs}{\allcomponents{x}}
-\newcommand*{\allYs}{\allcomponents{y}}
-\newcommand*{\allmus}{\allcomponents{\mu}}
-\newcommand*{\allMs}{\allcomponents{m}}
-\newcommand*{\allWs}{\allcomponents{w}}%
-\newcommand*{\allNsbut}[2][j]{\allbut[#1]{#2}{\Nt}}
-\newcommand*{\allXsbut}[2][j]{\allbutlastand[#1]{#2}{x}}
-\newcommand*{\allYsbut}[2][j]{\allbutlastand[#1]{#2}{y}}
-\newcommand*{\allmusbut}[2][j]{\allbut[#1]{#2}{\mu}}
-\newcommand*{\allMsbut}[2][j]{\allbut[#1]{#2}{m}}
-\newcommand*{\allWsbut}[2][j]{\allbutlastand[#1]{#2}{w}}%
-\newcommand*{\allcomponents}[1]{\vec{#1}}
-\newcommand*{\allbut}[3][j]{%
-  \def\tmp@arg{#2}%
-  \def\tmp@@arg{#1}%
-  \ifx\tmp@arg\tmp@@arg
-    {#3}_{k\neq #2}%
-  \else
-    {#3}_{#1\neq #2}%
-  \fi
-}
-\newcommand*{\allbutlastand}[3][j]{%
-  \edef\tmp@arg{#1}%
-  \edef\tmp@@arg{#2}%
-  \ifx\tmp@@arg\ncomponents
-    {#3}_{#1 \neq #2}%
-  \else
-    \ifx\tmp@arg\tmp@@arg
-      {#3}_{k \neq #2,\ncomponents}%
-    \else
-      {#3}_{#1 \neq #2,\ncomponents}%
-    \fi
-  \fi
+  \tl_set:Nn \l__thermodynamics_PartialOpen_tl {.}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {.}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {.}
+  \ExecuteOptions{nosubscripts}
+}
+\NewExpandableDocumentCommand \ncomponents {} {C}
+\NewDocumentCommand{\allNs}{O{i}}{\allcomponents[#1]{\Nt}}
+\NewDocumentCommand{\allXs}{O{i}}{\allcomponents[#1]{x}}
+\NewDocumentCommand{\allYs}{O{i}}{\allcomponents[#1]{y}}
+\NewDocumentCommand{\allmus}{O{i}}{\allcomponents[#1]{\mu}}
+\NewDocumentCommand{\allMs}{O{i}}{\allcomponents[#1]{m}}
+\NewDocumentCommand{\allWs}{O{i}}{\allcomponents[#1]{w}}
+\NewDocumentCommand{\allNsbut}{O{j} m} {\allbut[#1]{#2}{\Nt}}
+\NewDocumentCommand{\allXsbut}{O{j} m} {\allbutlastand[#1]{#2}{x}}
+\NewDocumentCommand{\allYsbut}{O{j} m} {\allbutlastand[#1]{#2}{y}}
+\NewDocumentCommand{\allmusbut}{O{j} m} {\allbut[#1]{#2}{\mu}}
+\NewDocumentCommand{\allMsbut}{O{j} m} {\allbut[#1]{#2}{m}}
+\NewDocumentCommand{\allWsbut}{O{j} m} {\allbutlastand[#1]{#2}{w}}
+\NewDocumentCommand{\allcomponents}{O{} m}{\vec{#2}}
+\NewDocumentCommand{\allbut}{O{j} m m}
+{ \tl_if_eq:nnTF {#1} {#2}
+  { {#3}\c_math_subscript_token{k \neq #2} }
+  { {#3}\c_math_subscript_token{#1 \neq #2} }
+}
+\NewDocumentCommand{\allbutlastand}{O{j} m m}
+{ \tl_if_eq:xxTF {#2} {\ncomponents}
+  { {#3}\c_math_subscript_token{#1 \neq #2} }
+  { \tl_if_eq:nnTF {#1} {#2}
+    { {#3}\c_math_subscript_token{k \neq #2,\ncomponents} }
+    { {#3}\c_math_subscript_token{#1 \neq #2,\ncomponents} }
+  }
 }
 \DeclareOption{moles-index}{}
-\DeclareOption{moles-range}{%
-  \renewcommand*{\allcomponents}[1]{{#1}_1,\dots,{#1}_{\ncomponents}}
-  \renewcommand*{\allbut}[3][j]{%
-    \def\@one{1}%
-    \edef\tmp@arg{#2}%
-    \ifx\tmp@arg\@one
-      {#3}_2,\dots,{#3}_{\ncomponents}%
-    \else
-      \ifx\tmp@arg\ncomponents
-        {#3}_1,\dots,{#3}_{\ncomponents-1}%
-      \else
-        {#3}_1,\dots,[{#3}_{#2}],\dots,{#3}_{\ncomponents}%
-      \fi
-    \fi
-  }
-  \renewcommand*{\allbutlastand}[3][j]{%
-    \def\@one{1}%
-    \edef\tmp@arg{#2}%
-    \edef\@ncminusone{\ncomponents-1}%
-    \ifx\tmp@arg\@one
-      {#3}_2,\dots,{#3}_{\ncomponents-1}%
-    \else
-      \ifx\tmp@arg\@ncminusone
-        {#3}_1,\dots,{#3}_{\ncomponents-2}%
-      \else
-        \ifx\tmp@arg\ncomponents
-          {#3}_1,\dots,{#3}_{\ncomponents-1}%
-      \else
-          {#3}_1,\dots,[{#3}_{#2}],\dots,{#3}_{\ncomponents}%
-        \fi
-      \fi
-    \fi
+\DeclareOption{moles-range}{ \__thermodynamics_set_moles_range }
+\cs_new:Npn \__thermodynamics_set_moles_range {%
+  \RenewDocumentCommand{\allcomponents}{O{} m}
+  { {##2}\c_math_subscript_token 1,\dots,
+        {##2}\c_math_subscript_token{\ncomponents} }
+  \RenewDocumentCommand{\allbut}{O{j} m m}
+  { \tl_if_eq:nnTF {##2} {1}
+    { {##3}\c_math_subscript_token 2,\dots,
+        {##3}\c_math_subscript_token{\ncomponents} }
+    { \tl_if_eq:xxTF {##2} {\ncomponents}
+      { {##3}\c_math_subscript_token 1,\dots,
+          {##3}\c_math_subscript_token{\ncomponents-1} }
+      { {##3}\c_math_subscript_token 1,\dots,
+            [{##3}\c_math_subscript_token{##2}],
+            \dots,{##3}\c_math_subscript_token{\ncomponents} }
+    }
+  }
+  \RenewDocumentCommand{\allbutlastand}{O{j} m m}
+  { \tl_if_eq:nnTF {##2} {1}
+    { {##3}\c_math_subscript_token 2,\dots,
+        {##3}\c_math_subscript_token{\ncomponents-1} }
+    { \tl_if_eq:xxTF {##2} {\ncomponents}
+      { {##3}\c_math_subscript_token 1,\dots,
+        {##3}\c_math_subscript_token{\ncomponents-1}
+      }
+      { \tl_if_eq:xxTF {##2} {\ncomponents-1}
+        { {##3}\c_math_subscript_token 1,\dots,
+          {##3}\c_math_subscript_token{\ncomponents-2} }
+        {
+          {##3}\c_math_subscript_token 1,\dots,
+          [{##3}\c_math_subscript_token{##2}],\dots,
+           {##3}\c_math_subscript_token{\ncomponents-1}
+        }
+      }
+    }
   }
 }
 \DeclareOption{Bejan}{
   \ExecuteOptions{EUFGHAN,intensive-lowercase,delta}
-  \let\@specific\MakeLowercase
-  \def\@intensive#1{\MakeLowercase{\bar #1}}
-  \AtEndOfPackage{
-    \DeclareSubscrSymbol{cV}{\bar\heatcapacitysymbol}{v}
-    \DeclareSubscrSymbol{cVs}{\heatcapacitysymbol}{v}
-    \DeclareSubscrSymbol{cVt}{\Nt\heatcapacitysymbol}{v}
-    \renewcommand*{\expansivitysymbol}{\beta}
-    \renewcommand*{\ncomponents}{n}
-  }
+  \cs_set:Nn \__thermodynamics_specific:n {\text_lowercase:n {#1}}
+  \cs_set:Nn \__thermodynamics_intensive:n {\bar{\text_lowercase:n {#1}}}
+  \tl_gset:Nn \g__thermodynamics_volume_symbol v
 }
 \DeclareOption{CBK}{
   \ExecuteOptions{EUAGHAN,intensive-lowercase}
   \AtEndOfPackage{
-    \let\thermo@overline\widetilde
-    \let\@specific\MakeLowercase
-    \renewcommand*{\@intensive}[1]{\MakeLowercase{\bar{#1}}}
-    \renewcommand*{\pressure@symbol}{p}
-    \renewcommand*{\Deltarxn}[1]{#1_R}
-    \renewcommand*{\compressibilitysymbol}{\beta}
-    \renewcommand*{\expansivitysymbol}{\alpha}
+    \cs_set:Nn \__thermodynamics_overline:n {\widetilde{#1}}
+    \cs_set:Nn \__thermodynamics_specific:n {\text_lowercase:n {#1}}
+    \cs_set:Nn \__thermodynamics_intensive:n {\bar{\text_lowercase:n{#1}}}
+    \tl_gset:Nn \g__thermodynamics_pressure_symbol p
+    \RenewDocumentCommand{\Deltarxn}{m}{{#1}\c_math_subscript_token R}
+    \RenewDocumentCommand{\compressibilitysymbol}{}{\beta}
+    \RenewDocumentCommand{\expansivitysymbol}{}{\alpha}
   }
 }
 \DeclareOption{ElliottLira}{
   \AtEndOfPackage{
-    \renewcommand*{\allcomponents}[1]{#1}
-    \renewcommand*{\Deltarxn}[1]{\Delta #1}
+    \RenewDocumentCommand{\allcomponents}{O{} m}{#2}
+    \RenewDocumentCommand{\Deltarxn}{m}{\Delta #1}
+    \RenewDocumentCommand{\IG}{}{{\text{ig}}}
+    \RenewDocumentCommand{\IGM}{}{{\text{ig}}}
+    \RenewDocumentCommand{\IS}{}{{\text{is}}}
   }
 }
 \DeclareOption{Koretsky}{
   \ExecuteOptions{EUAGHAn,brackets,intensive-lowercase,delta}
   \AtEndOfPackage{
-    \renewcommand*{\partialmolar}[1]{\gdef\pm@symbol{#1}\generic@pm}
-    \renewcommand*{\expansivitysymbol}{\beta}
-    \renewcommand*{\IS}{{\text{ideal}}}
-    \renewcommand*{\residual}{{\text{dep}}}
-    \renewcommand*{\IG}{{\text{ideal}}}
-    \renewcommand*{\IGM}{{\text{ideal}}}
-    \renewcommand*{\Deltafus}[1]{\Delta{#1}_\fusion}
-    \renewcommand*{\Deltasub}[1]{\Delta{#1}_\sublimation}
-    \renewcommand*{\Deltavap}[1]{\Delta{#1}_\vaporization}
-    \renewcommand*{\Henryrat}{{\mathcal{H}}}
-    \renewcommand*{\gammarat}{\gamma^\text{Henry's}}
-    \let\phipure\varphi
-    \renewcommand*{\phimix}{\hat\varphi}
-    \renewcommand*{\phisat}{\varphi^\sat}
-    \let\Delta@fus@sym\relax
-    \DeclareSubscrSymbol{@Deltafus}{\Delta@fus@sym}{\fusion}
-    \renewcommand*{\Deltafus}[1]{\def\Delta@fus@sym{\Delta #1}\@Deltafus}
-    \let\Delta@vap@sym\relax
-    \DeclareSubscrSymbol{@Deltavap}{\Delta@vap@sym}{\vaporization}
-    \renewcommand*{\Deltasub}[1]{\def\Delta@sub@sym{\Delta #1}\@Deltasub}
-    \let\Delta@sub@sym\relax
-    \DeclareSubscrSymbol{@Deltasub}{\Delta@sub@sym}{\sublimation}
-    \renewcommand*{\Deltasub}[1]{\def\Delta@sub@sym{\Delta #1}\@Deltasub}
+    %^^A Undo part of intensive-lowercase
+    \RenewDocumentCommand{\partialmolar}{m}
+    { \tl_set:Nn \l__thermodynamics_pm_symbol_tl {#1}
+      \__thermodynamics_generic_pm:
+    }
+    \RenewDocumentCommand{\expansivitysymbol}{}{\beta}
+    \RenewDocumentCommand{\IS}{}{{\text{ideal}}}
+    \RenewDocumentCommand{\residual}{}{{\text{dep}}}
+    \RenewDocumentCommand{\IG}{}{{\text{ideal}}}
+    \RenewDocumentCommand{\IGM}{}{{\text{ideal}}}
+    \RenewDocumentCommand{\Henryrat}{}{{\mathcal{H}}}
+    \RenewDocumentCommand{\gammarat}{}
+        {\gamma\c_math_superscript_token\text{Henry's}}
+    \RenewDocumentCommand{\phipure}{}{\varphi}
+    \RenewDocumentCommand{\phimix}{}{\hat\varphi}
+    \RenewDocumentCommand{\phisat}{}{\varphi\c_math_superscript_token\sat}
+    \cs_new:Npn \Delta_fus_sym {} {}
+    \NewSubscriptedSymbol{\Delta_fus}{\Delta_fus_sym}{\fusion}
+    \RenewDocumentCommand{\Deltafus}{m}{
+      \cs_set:Npn \Delta_fus_sym {} { \Delta #1 }
+      \Delta_fus
+    }
+    \cs_new:Npn \Delta_vap_sym {} {}
+    \NewSubscriptedSymbol{\Delta_vap}{\Delta_vap_sym}{\vaporization}
+    \RenewDocumentCommand{\Deltavap}{m}{
+      \cs_set:Npn \Delta_vap_sym {} { \Delta #1 }
+      \Delta_vap
+    }
+    \cs_new:Npn \Delta_sub_sym {} {}
+    \NewSubscriptedSymbol{\Delta_sub}{\Delta_sub_sym}{\sublimation}
+    %^^A Undo part of intensive-lowercase
+    \RenewDocumentCommand{\Deltasub}{m}{
+      \cs_set:Npn \Delta_sub_sym {} { \Delta #1 }
+      \Delta_sub
+    }
   }
 }
 \DeclareOption{MSBB}{
   \ExecuteOptions{EUFGHAn,intensive-lowercase,delta}
   \AtEndOfPackage{
-    \renewcommand*{\IGM}{\ast}
-    \renewcommand*{\IG}{\ast}
-    \renewcommand*{\expansivitysymbol}{\beta}
-    \renewcommand*{\allcomponents}[1]{#1}
-    \renewcommand*{\allbut}[3][j]{%
-      \def\tmp@arg{#2}%
-      \def\tmp@@arg{#1}%
-      \ifx\tmp@arg\tmp@@arg
-        {#3}_{k}%
-      \else
-        {#3}_{#1}%
-      \fi
-    }
-    \let\Helmholtz@symbol\psi
-    \renewcommand*{\Ft}{\Psi}
-    \def\@intensive#1{\MakeLowercase{\thermo@overline #1}}
-    \let\@specific\MakeLowercase
-    \renewcommand*{\partialmolar}[1]{\gdef\pm@symbol{#1}\generic@pm}
-    \renewcommand*{\fmix}{\bar f}
-    \renewcommand*{\phimix}{\bar\phi}
-    \renewcommand*{\pressure@symbol}{p}
+    \RenewDocumentCommand{\IGM}{}{\ast}
+    \RenewDocumentCommand{\IG}{}{\ast}
+    \RenewDocumentCommand{\expansivitysymbol}{}{\beta}
+    \RenewDocumentCommand{\allcomponents}{O{} m}{#2}
+    \RenewDocumentCommand{\allbut}{O{j} m m}
+    {
+      \tl_if_eq:nnTF {#1} {#2}
+      { {#3}\c_math_subscript_token k }
+      { {#3}\c_math_subscript_token{#1} }
+    }
+    \tl_gset_eq:NN \g__thermodynamics_Helmholtz_symbol \psi
+    \RenewDocumentCommand{\Ft}{}{\Psi}
+    \cs_set:Nn \__thermodynamics_intensive:n {\__thermodynamics_overline:n{\text_lowercase:n{#1}}}
+    \cs_set:Nn \__thermodynamics_specific:n {\text_lowercase:n{#1}}
+    \RenewDocumentCommand{\fmix}{}{\bar f}
+    \RenewDocumentCommand{\phimix}{}{\bar\phi}
+    \RenewDocumentCommand{\phimix}{}{\bar\phi}
+    \tl_gset:Nn \g__thermodynamics_pressure_symbol p
+    \RenewDocumentCommand{\partialmolar}{m}
+    {
+      \tl_set:Nn \l__thermodynamics_pm_symbol_tl {#1}
+      \__thermodynamics_generic_pm:
+    }
   }
 }
 \DeclareOption{Prausnitz}{
   \ExecuteOptions{intensive-lowercase}
   \AtEndOfPackage{
-    \renewcommand*{\fmix}{f}
-    \let\phimix\phi
-    \renewcommand*{\fsat}{\fpure^\sat}
-    \DeclareSubscrSymbol{fpure}{f}{{\text{pure}}}
-    \DeclareSubscrSymbol{phipure}{\phi}{{\text{pure}}}
-    \renewcommand*{\residual}{{{\mathcal{R}}}}
-    \renewcommand*{\allcomponents}[1]{{#1}_i}
-    \renewcommand*{\allbut}[3][j]{%
-      \def\tmp@arg{#2}%
-      \def\tmp@@arg{#1}%
-      \ifx\tmp@arg\tmp@@arg
-        {#3}_{k}%
-      \else
-        {#3}_{#1}%
-      \fi
+    \RenewDocumentCommand{\fmix}{}{f}
+    \RenewDocumentCommand{\phimix}{}{\phi}
+    \RenewDocumentCommand{\fsat}{}{\fpure\c_math_superscript_token\sat}
+    % TODO: this should pick up H_2 and make it into H_{2,1} (assuming the
+    % solvent is always 1...?)
+    \RenewDocumentCommand{\Henryrat}{}{H}
+    \RenewDocumentCommand{\residual}{}{{{\mathcal{R}}}}
+    \RenewDocumentCommand{\allcomponents}{O{i} m}
+      { {#2}\c_math_subscript_token{#1} }
+    \RenewDocumentCommand{\allbut}{O{i} m m}
+    { \tl_if_eq:nnTF {#1} {#2}
+        { {#3}\c_math_subscript_token k }
+        { {#3}\c_math_subscript_token{#1} }
     }
+    \RenewSubscriptedSymbol{\fpure}{f}{{\text{pure}}}
+    \RenewSubscriptedSymbol{\phipure}{\phi}{{\text{pure}}}
   }
 }
 \DeclareOption{Sandler}{
   \ExecuteOptions{EUAGHaN,extensive-plain}
   \AtEndOfPackage{
-    \renewcommand*{\sat}{{\text{vap}}}
-    \renewcommand*{\excess}{{\text{{ex}}}}
-    \renewcommand*{\residual}{{\text{r}}}
-    \renewcommand*{\ncomponents}{\mathcal{C}}
-    \renewcommand*{\fmix}{\bar f}
-    \renewcommand*{\fstd}{\bar f^\circ}
-    \renewcommand*{\phimix}{\bar\phi}
-    \renewcommand*{\allcomponents}[1]{\thermo@underline{#1}}
-    \renewcommand*{\IG}{{\text{IG}}}
-    \renewcommand*{\IGM}{{\text{IGM}}}
-    \renewcommand*{\IS}{{\text{IM}}}
-    \renewcommand*{\Deltamix}[1]{\Delta_\mixing #1}
-    \renewcommand*{\Deltarxn}[1]{\Delta_\reaction #1}
-    \renewcommand*{\Deltasub}[1]{\Delta_\sublimation #1}
-    \renewcommand*{\Deltafus}[1]{\Delta_\fusion #1}
-    \renewcommand*{\Deltavap}[1]{\Delta_\vaporization #1}
-    \renewcommand*{\Henryrat}{H}
-    \DeclareSubscrSymbol{cV}{\heatcapacitysymbol}{\volume@symbol}
-    \DeclareSubscrSymbol{cP}{\heatcapacitysymbol}{\pressure@symbol}
-    \DeclareSubscrSymbol{cVt}{\Nt\heatcapacitysymbol}{\volume@symbol}
-    \DeclareSubscrSymbol{cPt}{\Nt\heatcapacitysymbol}{\pressure@symbol}
+    \RenewDocumentCommand{\sat}{}{{\text{vap}}}
+    \RenewDocumentCommand{\excess}{}{{\text{ex}}}
+    \RenewDocumentCommand{\residual}{}{{\text{r}}}
+    \RenewExpandableDocumentCommand{\ncomponents}{}{\mathcal{C}}
+    \RenewDocumentCommand{\fmix}{}{\bar f}
+    \RenewDocumentCommand{\fstd}{}{\bar f\c_math_superscript_token\std}
+    \RenewDocumentCommand{\phimix}{}{\bar\phi}
+    \RenewDocumentCommand{\allcomponents}{O{} m}{\__thermodynamics_underline:n{#2}}
+    \RenewDocumentCommand{\IG}{}{{\text{IG}}}
+    \RenewDocumentCommand{\IGM}{}{{\text{IGM}}}
+    \RenewDocumentCommand{\IS}{}{{\text{IM}}}
+    \RenewDocumentCommand{\Deltamix}{m}
+        {\Delta\c_math_subscript_token\mixing #1}
+    \RenewDocumentCommand{\Deltarxn}{m}
+        {\Delta\c_math_subscript_token\reaction #1}
+    \RenewDocumentCommand{\Deltasub}{m}
+        {\Delta\c_math_subscript_token\sublimation #1}
+    \RenewDocumentCommand{\Deltafus}{m}
+        {\Delta\c_math_subscript_token\fusion #1}
+    \RenewDocumentCommand{\Deltavap}{m}
+        {\Delta\c_math_subscript_token\vaporization #1}
+    \RenewDocumentCommand{\Henryrat}{}{H}
+    \RenewSubscriptedSymbol{\cV}
+        {\heatcapacitysymbol}{\g__thermodynamics_volume_symbol}
+    \RenewSubscriptedSymbol{\cP}
+        {\heatcapacitysymbol}{\g__thermodynamics_pressure_symbol}
+    \RenewSubscriptedSymbol{\cVt}
+        {\Nt\heatcapacitysymbol}{\g__thermodynamics_volume_symbol}
+    \RenewSubscriptedSymbol{\cPt}
+        {\Nt\heatcapacitysymbol}{\g__thermodynamics_pressure_symbol}
   }
 }
 \DeclareOption{SVNAS}{
   \ExecuteOptions{extensive-superscript}
   \AtEndOfPackage{
-    \renewcommand*{\allcomponents}[1]{#1}
-    \renewcommand*{\allbut}[3][j]{%
-      \def\tmp@arg{#2}%
-      \def\tmp@@arg{#1}%
-      \ifx\tmp@arg\tmp@@arg
-        {#3}_{k}%
-      \else
-        {#3}_{#1}%
-      \fi
-    }
-    \renewcommand*{\IG}{{ig}}
-    \renewcommand*{\IGM}{{ig}}
-    \renewcommand*{\IS}{{id}}
-    \renewcommand*{\expansivitysymbol}{\beta}
-    \renewcommand*{\Deltarxn}[1]{\Delta #1}
-    \DeclareSubscrSymbol{cVt}{\Nt\heatcapacitysymbol}{\volume@symbol}
-    \DeclareSubscrSymbol{cPt}{\Nt\heatcapacitysymbol}{\pressure@symbol}
+    \RenewDocumentCommand{\allcomponents}{O{} m}{#2}
+    \RenewDocumentCommand{\allbut}{O{j} m m}
+    {
+      \tl_if_eq:nnTF {#1} {#2}
+      { {#3}\c_math_subscript_token k }
+      { {#3}\c_math_subscript_token{#1} }
+    }
+    \RenewDocumentCommand{\IG}{}{{ig}}
+    \RenewDocumentCommand{\IGM}{}{{ig}}
+    \RenewDocumentCommand{\IS}{}{{id}}
+    \RenewDocumentCommand{\expansivitysymbol}{}{\beta}
+    \RenewDocumentCommand{\Deltarxn}{m}{\Delta #1}
+    \RenewSubscriptedSymbol{\cVt}
+        {\Nt\heatcapacitysymbol}{\g__thermodynamics_volume_symbol}
+    \RenewSubscriptedSymbol{\cPt}
+        {\Nt\heatcapacitysymbol}{\g__thermodynamics_pressure_symbol}
   }
 }
 \DeclareOption{TesterModell}{
   \ExecuteOptions{EUAGHaN,delta}
   \AtEndOfPackage{
-    \renewcommand*{\ncomponents}{n}
-    \renewcommand*{\allcomponents}[1]{{#1}_i}
-    \renewcommand*{\allbut}[3][j]{%
-      \def\tmp@arg{#2}%
-      \def\tmp@@arg{#1}%
-      \ifx\tmp@arg\tmp@@arg
-        {#3}_k\relax[#2]
-      \else
-        {#3}_{#1}\relax[#2]
-      \fi
-    }
-    \renewcommand*{\allbutlastand}[3][j]{%
-      \edef\tmp@arg{#1}%
-      \edef\tmp@@arg{#2}%
-      \ifx\tmp@@arg\ncomponents
-        {#3}_{#1}\relax[#2]%
-      \else
-        \ifx\tmp@arg\tmp@@arg
-          {#3}\relax[#2,\ncomponents]%
-        \else
-          {#3}\relax[#2,\ncomponents]%
-        \fi
-      \fi
-    }
-    \renewcommand*{\IG}{{ig}}
-    \renewcommand*{\IGM}{{igm}}
-    \renewcommand*{\IS}{{ID}}
-    \renewcommand*{\excess}{{EX}}%
-    \renewcommand*{\reaction}{{rx}}
-    \renewcommand*{\Henryrat}{f^{\ast\ast}}
-    \renewcommand*{\Henrymol}{f^\ast}
-    \renewcommand*{\gammarat}{\gamma^{\ast\ast}}
-    \renewcommand*{\gammamol}{\gamma^\ast}
+    \RenewExpandableDocumentCommand{\ncomponents}{}{n}
+    \RenewDocumentCommand{\allcomponents}{O{i} m}
+    {
+      {#2}\c_math_subscript_token{#1}
+    }
+    \RenewDocumentCommand{\allbut}{O{i} m m}
+    { \tl_if_eq:nnTF {#1} {#2}
+      { {#3}\c_math_subscript_token{k}[#2] }
+      { {#3}\c_math_subscript_token{#1}[#2] }
+    }
+    \RenewDocumentCommand{\allbutlastand}{O{j} m m}
+    { \tl_if_eq:xxTF {#2} {\ncomponents}
+      { {#3}\c_math_subscript_token{#1}\relax[#2] }
+      { \tl_if_eq:nnTF {#1} {#2}
+        { {#3}\c_math_subscript_token{k}[#2,\ncomponents] }
+        { {#3}\c_math_subscript_token{#1}[#2,\ncomponents] }
+      }
+    }
+    \RenewDocumentCommand{\IG}{}{{o}}
+    \RenewDocumentCommand{\IGM}{}{{o}}
+    \RenewDocumentCommand{\IS}{}{{ID}}
+    \RenewDocumentCommand{\excess}{}{{EX}}
+    \RenewDocumentCommand{\reaction}{}{{rx}}
+    \RenewDocumentCommand{\Henryrat}{}
+        {f\c_math_superscript_token{\ast\ast}}
+    \RenewDocumentCommand{\Henrymol}{}{f\c_math_superscript_token\ast}
+    \RenewDocumentCommand{\gammarat}{}
+        {\gamma\c_math_superscript_token{\ast\ast}}
+    \RenewDocumentCommand{\gammamol}{}
+        {\gamma\c_math_superscript_token\ast}
+    \RenewExpandableDocumentCommand{\JTsymbol}{}{\alpha}
+    \RenewSubscriptedSymbol{\muJT}{\JTsymbol}{H}
   }
 }
 \DeclareOption{Thompson}{
   \ExecuteOptions{EUAGHAn,delta}
-  \AtEndOfPackage{
-    \renewcommand*{\excess}{{EX}}
-    \renewcommand*{\residual}{{R}}
-    \renewcommand*{\allcomponents}[1]{{#1}_j}
-    \renewcommand*{\ncomponents}{c}
-    \renewcommand*{\IS}{{IS}}
-    \renewcommand*{\IG}{{IG}}
-    \let\IGM\IG
-    \def\@fpure_#1{f_{#1}\@ifnextchar^{}{^\bullet}}
-    \renewcommand*{\fpure}{\@ifnextchar_{\@fpure}{f}}
-    \def\@phi@pure_#1{\phi_{#1}\@ifnextchar^{}{^\bullet}}
-    \renewcommand*{\phipure}{\@ifnextchar_{\@phi@pure}{\phi}}
-    \renewcommand*{\mixing}{{MIX}}
-    \renewcommand*{\Deltamix}[1]{\Delta_\mixing #1}
-    \renewcommand*{\Deltarxn}[1]{\Delta #1}
-    \def\@@intensive_#1{_{#1}\@ifnextchar^{}{^\bullet}}
-    \newcommand*{\@intensive}[1]{#1\@ifnextchar_{\@@intensive}{}}
-    \renewcommand*{\allbut}[3][j]{%
-      \def\tmp@arg{#2}%
-      \def\tmp@@arg{#1}%
-      \ifx\tmp@arg\tmp@@arg
-        {#3}_{k}\neq{#3}_{#2}%
-      \else
-        {#3}_{#1}\neq{#3}_{#2}%
-      \fi
+  \AtEndOfPackage
+  {
+    \RenewDocumentCommand{\excess}{}{{EX}}
+    \RenewDocumentCommand{\residual}{}{{R}}
+    %^^A He uses k_H for both types of Henry's constant, but I changed
+    %^^A the rational basis one just so there is SOME difference
+    \RenewSubscriptedSymbol{\Henryrat}{k}{h}
+    \RenewSubscriptedSymbol{\Henrymol}{k}{H}
+    \RenewDocumentCommand{\allcomponents}{O{j} m}
+    {
+      {#2}\c_math_subscript_token{#1}
+    }
+    \RenewDocumentCommand{\allNs}{O{j}}{\allcomponents[#1]{\Nt}}
+    \RenewDocumentCommand{\allXs}{O{j}}{\allcomponents[#1]{x}}
+    \RenewDocumentCommand{\allYs}{O{j}}{\allcomponents[#1]{y}}
+    \RenewDocumentCommand{\allmus}{O{j}}{\allcomponents[#1]{\mu}}
+    \RenewDocumentCommand{\allMs}{O{j}}{\allcomponents[#1]{m}}
+    \RenewDocumentCommand{\allWs}{O{j}}{\allcomponents[#1]{w}}
+    \RenewExpandableDocumentCommand{\ncomponents}{}{c}
+    \RenewDocumentCommand{\IS}{}{{IS}}
+    \RenewDocumentCommand{\IG}{}{{IG}}
+    \RenewDocumentCommand{\IGM}{}{{IG}}
+    \cs_new:Nn \__thermodynamics_fpure_one:n
+    {
+      f\c_math_subscript_token{#1}
+      \peek_catcode_remove:NF \c_math_superscript_token
+      { \c_math_superscript_token\bullet }
+    }
+    \RenewDocumentCommand{\fpure}{}
+    {
+      \peek_catcode_remove:NTF \c_math_subscript_token
+      { \__thermodynamics_fpure_one:n }
+      { f }
+    }
+    \cs_new:Nn \__thermodynamics_intensive_two:n
+    {
+      \c_math_subscript_token{#1}
+      \peek_catcode:NF \c_math_superscript_token
+      {
+        \c_math_superscript_token\bullet
+      }
+    }
+    \cs_set:Nn \__thermodynamics_intensive:n
+    { #1
+      \peek_catcode_remove:NT \c_math_subscript_token
+      { \__thermodynamics_intensive_two:n }
+    }
+    \cs_new:Nn \__thermodynamics_phipure_one:n
+    {
+      \phi\c_math_subscript_token{#1}
+      \peek_catcode:NF \c_math_superscript_token
+      { \c_math_superscript_token\bullet }
+    }
+    \RenewDocumentCommand{\phipure}{}
+    {
+      \peek_catcode_remove:NTF \c_math_subscript_token
+      {
+        \__thermodynamics_phipure_one:n
+      }
+      {\phi}
+    }
+    \RenewDocumentCommand{\mixing}{}{{MIX}}
+    \RenewDocumentCommand{\Deltamix}{m}
+        {\Delta\c_math_subscript_token\mixing #1}
+    \RenewDocumentCommand{\Deltarxn}{m}{\Delta #1}
+    \RenewDocumentCommand{\allbut}{O{j} m m}
+    { \tl_if_eq:nnTF {#1} {#2}
+      {
+        {#3}\c_math_subscript_token k\neq{#3}\c_math_subscript_token{#2}
+      }
+      {
+        {#3}\c_math_subscript_token{#1}\neq{#3}\c_math_subscript_token{#2}
+      }
     }
   }
 }
 \ExecuteOptions{EUAGHan,subscripts,parentheses,intensive-plain,moles-index}
 \ProcessOptions
-\newlength{\Partial@const@width}
-\newlength{\operator@width}
-\settowidth{\operator@width}{=}
-\newlength{\adjust@width}
-\setlength{\adjust@width}{0.1\operator@width}
-\addtolength{\operator@width}{\adjust@width}
-\def\Partial@start{\left\PartialOpen}
-\def\Partial@end{\right\PartialClose}
-\def\Partial@empty@end{\right\PartialEmptyClose}
-\def\Partial{\@ifstar\Partial@star\Partial@nostar}
-\newif\iftwo@has@Nt
-\two@has@Ntfalse
-\newif\iftwo@has@xory
-\two@has@xoryfalse
-\newif\ifthree@has@Nt
-\three@has@Ntfalse
-\newif\ifthree@has@xory
-\three@has@xoryfalse
-\AtEndOfPackage{%
-  \edef\thermo@Nt{\Nt}%
-  \edef\thermo@x{x}%
-  \edef\thermo@y{y}%
-}
-\def\thermo@parse@two#1\relax{%
-  \@tfor\@i:=#1\do{%
-    \edef\@@i{\@i}%
-    \ifx\@@i\thermo@Nt
-      \two@has@Nttrue
-      \@break@tfor
-    \fi
-    \ifx\@@i\thermo@x
-      \two@has@xorytrue
-      \@break@tfor
-    \fi
-    \ifx\@@i\thermo@y
-      \two@has@xorytrue
-      \@break@tfor
-    \fi
-  }
-}
-\newcommand*{\Partial@nostar}[3]{%
-  \def\tmp@arg{#3}%
-  \if@subscripted
-    % Handles situation of empty variables held constant
-    \ifx\tmp@arg\@empty
-      \ensuremath{\Partial@start\frac{\partial #1}
-                                     {\partial #2}\Partial@empty@end}%
-    \else
-      \ensuremath{\Partial@start\frac{\partial #1}
-                                     {\partial #2}\Partial@end_{#3}}%
-    \fi
-  \else
-    % If not subscripted, we put the arguments (if any) in the derivative
-    \ifx\tmp@arg\@empty
-      \ensuremath{\Partial@start\frac{\partial #1}
-                                     {\partial #2}\Partial@empty@end}%
-    \else
-      % Check for whether #3 contains \allNsbut{i}/etc. and #2 is \Nt_i/etc.
-      \thermo@parse@two#2\relax
-      \iftwo@has@Nt
-        \renewcommand*{\allbut}[3][j]{\allcomponents{##3}}%
-        \ensuremath{\Partial@start\frac{\partial #1(#3)}
-                                       {\partial #2}\Partial@end}%
-      \else
-        \iftwo@has@xory
-          \renewcommand*{\allbutlastand}[3][j]{\allbut{\ncomponents}{##3}}%
-          \ensuremath{\Partial@start\frac{\partial #1(#3)}
-                                         {\partial #2}\Partial@end}%
-        \else
-          \ensuremath{\Partial@start\frac{\partial #1(#2,#3)}
-                                         {\partial #2}\Partial@end}%
-        \fi
-      \fi
-    \fi
-  \fi
-}
-\newcommand*{\Partial@star}[3]{%
-  \settowidth{\Partial@const@width}{\ensuremath{#3}}%
-  \addtolength{\Partial@const@width}{-0.15\Partial@const@width}%
-  \Partial@nostar{#1}{#2}{#3}%
-  \if@subscripted
-    \ifdim\operator@width<\Partial@const@width
-      \kern -\operator@width
-    \else
-      \kern -\Partial@const@width
-    \fi
-  \fi
-}
-\def\PartialBigg{%
-  \def\Partial@start{\Biggl\PartialOpen}%
-  \def\Partial@end{\Biggr\PartialClose}%
-  \def\Partial@empty@end{\Biggr\PartialClose}%
-  \Partial%
-}
-\def\Partialbigg{%
-  \def\Partial@start{\biggl\PartialOpen}%
-  \def\Partial@end{\biggr\PartialClose}%
-  \def\Partial@empty@end{\biggr\PartialClose}%
-  \Partial%
-}
-\def\PartialSecond{\@ifstar\PartialSecond@star\PartialSecond@nostar}
-\newcommand*{\PartialSecond@nostar}[3]{%
-  \def\tmp@arg{#3}%
-  \if@subscripted
-  % Handles situation of empty variables held constant
-    \ifx\tmp@arg\@empty
-        \ensuremath{\Partial@start\frac{\partial^2 #1}
-                                       {\partial #2^2}\Partial@empty@end}%
-    \else
-        \ensuremath{\Partial@start\frac{\partial^2 #1}
-                                       {\partial #2^2}\Partial@end_{#3}}%
-    \fi
-  \else
-    \ifx\tmp@arg\@empty
-        \ensuremath{\Partial@start\frac{\partial^2 #1}
-                                       {\partial #2^2}\Partial@empty@end}%
-    \else
-      % Check for whether #3 contains \allNsbut{i}/etc. and #2 is \Nt_i/etc.
-      \thermo@parse@two#2\relax
-      \iftwo@has@Nt
-        \renewcommand*{\allbut}[3][j]{\allcomponents{##3}}%
-        \ensuremath{\Partial@start\frac{\partial^2 #1(#3)}
-                                       {\partial #2^2}\Partial@end}%
-      \else
-        \iftwo@has@xory
-          \renewcommand*{\allbutlastand}[3][j]{\allbut{\ncomponents}{##3}}%
-          \ensuremath{\Partial@start\frac{\partial^2 #1(#3)}
-                                         {\partial #2^2}\Partial@end}%
-        \else
-          \ensuremath{\Partial@start\frac{\partial^2 #1(#2,#3)}
-                                         {\partial {#2}^2}\Partial@end}%
-        \fi
-      \fi
-    \fi
-  \fi
-}
-\newcommand*{\PartialSecond@star}[3]{%
-    \settowidth{\Partial@const@width}{\ensuremath{#3}}%
-    \addtolength{\Partial@const@width}{-0.15\Partial@const@width}%
-    \PartialSecond@nostar{#1}{#2}{#3}%
-    \if@subscripted
-      \ifdim\operator@width<\Partial@const@width
-        \kern -\operator@width
-      \else
-        \kern -\Partial@const@width
-      \fi
-    \fi
-}
-\def\PartialSecondBigg{%
-  \def\Partial@start{\expandafter\Biggl\PartialOpen}%
-  \def\Partial@end{\expandafter\Biggr\PartialClose}%
-  \PartialSecond%
-}
-\def\PartialSecondbigg{%
-  \def\Partial@start{\expandafter\biggl\PartialOpen}%
-  \def\Partial@end{\expandafter\biggr\PartialClose}%
-  \PartialSecond%
-}
-\def\PartialMixSecond{\@ifstar\PartialMixSecond@star\PartialMixSecond@nostar}
-\newcommand*{\PartialMixSecond@nostar}[4]{%
-  \def\tmp@arg{#4}%
-  \if@subscripted
-  % Handles situation of empty variables held constant
-    \ifx\tmp@arg\@empty
-      \ensuremath{\Partial@start\frac{\partial^2 #1}
-                           {\partial #2\partial#3}\Partial@empty@end}%
-    \else
-      \ensuremath{\Partial@start\frac{\partial^2 #1}
-                           {\partial #2\partial#3}\Partial@end_{#4}}%
-    \fi
-  \else
-    \ifx\tmp@arg\@empty
-      \ensuremath{\Partial@start\frac{\partial^2 #1(#2,#3)}
-                           {\partial #2\partial#3}\Partial@empty@end}%
-    \else
-      % This time, we check whether #2 OR #3 are \Nt_i/etc.
-      \thermo@parse@two#3\relax
-      \iftwo@has@Nt\three@has@Nttrue\fi
-      \iftwo@has@xory\three@has@xorytrue\fi
-      \two@has@Ntfalse
-      \two@has@xoryfalse
-      \thermo@parse@two#2\relax
-      \iftwo@has@Nt
-        \renewcommand*{\allbut}[3][j]{\allcomponents{##3}}%
-        \ensuremath{\Partial@start\frac{\partial^2 #1(#3,#4)}
-                                       {\partial #2\partial#3}\Partial@end}%
-      \else
-        \iftwo@has@xory
-          \renewcommand*{\allbutlastand}[3][j]{\allbut{\ncomponents}{##3}}%
-          \ensuremath{\Partial@start\frac{\partial^2 #1(#3,#4)}
-                                         {\partial #2\partial#3}\Partial@end}%
-        \else
-          \ifthree@has@Nt
-            \renewcommand*{\allbut}[3][j]{\allcomponents{##3}}%
-            \ensuremath{\Partial@start\frac{\partial^2 #1(#2,#4)}
-                                      {\partial #2\partial#3}\Partial@end}%
-          \else
-            \ifthree@has@xory
-              \PackageWarning{thermodynamics}{GOT HERE}
-              %\renewcommand*{\allbutlastand}[3][j]{\allbut{\ncomponents}{##3}}%
-              \renewcommand*{\allbutlastand}[3][j]{SCREW YOU}%
-              \ensuremath{\Partial@start\frac{\partial^2 #1(#2,#4)}
-                                        {\partial #2\partial#3}\Partial@end}%
-            \else
-              \ensuremath{\Partial@start\frac{\partial^2 #1(#2,#3,#4)}
-                                        {\partial #2\partial#3}\Partial@end}%
-            \fi
-          \fi
-        \fi
-      \fi
-    \fi
-  \fi
-}
-\newcommand*{\PartialMixSecond@star}[4]{%
-    \settowidth{\Partial@const@width}{\ensuremath{#4}}%
-    \addtolength{\Partial@const@width}{-0.25\Partial@const@width}%
-    \PartialMixSecond@nostar{#1}{#2}{#3}{#4}%
-    \if@subscripted
-      \ifdim\operator@width<\Partial@const@width
-        \kern -\operator@width
-      \else
-        \kern -\Partial@const@width
-      \fi
-    \fi
-}
-\def\PartialMixSecondBigg{%
-  \def\Partial@start{\expandafter\Biggl\PartialOpen}%
-  \def\Partial@end{\expandafter\Biggr\PartialClose}%
-  \PartialMixSecond%
-}
-\def\PartialMixSecondbigg{%
-  \def\Partial@start{\expandafter\biggl\PartialOpen}%
-  \def\Partial@end{\expandafter\biggr\PartialClose}%
-  \PartialMixSecond%
+\tl_const:Nn \c__thermodynamics_sort_order_tl
+    {\Et\Em\Es\Ut\Um\Us\Ht\Hm\Hs\Ft\Fm\Fs\Gt\Gm\Gs\Lt\Lm\Ls T\St\Sm\Ss
+        P\Vt\Vm\Vs\mu\Nt mwxyz\At\Am\As\sigma
+        ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklnopqrstuvwxyz}
+\clist_new:N \l__thermodynamics_in_list_clist
+\clist_new:N \l__thermodynamics_sorted_list_clist
+\clist_new:N \l__thermodynamics_remaining_list_clist
+\cs_new:Nn \__thermodynamics_sort_clist:n
+{% Sort the list in the order of \c__thermodynamics_sort_order_tl
+
+  % Wipe out any remnants from the last sort
+  \clist_clear:N \l__thermodynamics_in_list_clist
+  \clist_clear:N \l__thermodynamics_sorted_list_clist
+
+  % Make a copy of the list
+  \clist_set:Nn \l__thermodynamics_remaining_list_clist {#1}
+
+  % Make a list of everything that's in the known sort order list
+  % and put everything else in the "not in sort order list" list.
+  \tl_map_inline:Nn \c__thermodynamics_sort_order_tl
+  {
+    \clist_if_in:NnT \l__thermodynamics_remaining_list_clist {##1}
+    { \clist_put_right:Nn \l__thermodynamics_in_list_clist {##1} }
+
+    \clist_remove_all:Nn \l__thermodynamics_remaining_list_clist {##1}
+  }
+
+  % Then merge the lists back together again.
+  \clist_if_empty:NF \l__thermodynamics_in_list_clist
+  {
+    \clist_put_right:Nn \l__thermodynamics_sorted_list_clist \l__thermodynamics_in_list_clist
+  }
+  \clist_if_empty:NF \l__thermodynamics_remaining_list_clist
+  {
+    \clist_put_right:Nn \l__thermodynamics_sorted_list_clist \l__thermodynamics_remaining_list_clist
+  }
+  \clist_use:Nn \l__thermodynamics_sorted_list_clist ,
+}
+\dim_new:N \l__thermodynamics_Partial_const_dim
+\dim_new:N \l__thermodynamics_operator_width_dim
+\dim_new:N \l__thermodynamics_adjust_width_dim
+\settowidth{\l__thermodynamics_operator_width_dim}{=}
+\dim_set:Nn \l__thermodynamics_adjust_width_dim {0.1\l__thermodynamics_operator_width_dim}
+\dim_add:Nn \l__thermodynamics_operator_width_dim \l__thermodynamics_adjust_width_dim
+\tl_new:N \l__thermodynamics_Partial_start_tl
+\tl_new:N \l__thermodynamics_Partial_end_tl
+\tl_new:N \l__thermodynamics_Partial_empty_end_tl
+\tl_new:N \l__thermodynamics_Partial_middle_tl
+\tl_set:Nn \l__thermodynamics_Partial_start_tl {\left\l__thermodynamics_PartialOpen_tl}
+\tl_set:Nn \l__thermodynamics_Partial_end_tl {\right\l__thermodynamics_PartialClose_tl}
+\tl_set:Nn \l__thermodynamics_Partial_empty_end_tl {\right\l__thermodynamics_PartialEmptyClose_tl}
+\tl_set:Nn \l__thermodynamics_Partial_middle_tl {\middle}
+\cs_set_eq:NN \__thermodynamics_frac:nn \frac
+\NewDocumentCommand{\Partial}{s m m m}
+{ \bool_if:nTF {#1}
+  {% Starred form (recursive)
+    \settowidth{\l__thermodynamics_Partial_const_dim}{\ensuremath{#4}}%
+    \dim_add:Nn \l__thermodynamics_Partial_const_dim {-0.20\l__thermodynamics_Partial_const_dim}%
+    \Partial{#2}{#3}{#4}%
+    \bool_if:NT \l__thermodynamics_subscripted_bool
+    { \dim_compare:nNnTF \l__thermodynamics_operator_width_dim
+                       < \l__thermodynamics_Partial_const_dim
+      { \kern -\l__thermodynamics_operator_width_dim }
+      { \kern -\l__thermodynamics_Partial_const_dim }
+    }
+  }
+  {% Unstarred form
+    \bool_if:NTF \l__thermodynamics_subscripted_bool
+    {% Handle case of empty variables held constant
+      \tl_if_eq:nnTF {#4} {}
+      { \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial #2}{\partial #3}\l__thermodynamics_Partial_empty_end_tl
+      }
+      { \l__thermodynamics_Partial_start_tl\__thermodynamics_frac:nn{\partial #2}
+                                         {\partial #3}\l__thermodynamics_Partial_end_tl
+        \c_math_subscript_token{#4}%
+      }
+    }
+    {% Check whether #4 contains \allNsbut{i} and #3 is \Nt_i
+      \tl_if_in:nnTF {#3} {\Nt}
+      { \RenewDocumentCommand{\allbut}{O{j} m m}{\allcomponents{##3}}
+        \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial #2(\__thermodynamics_sort_clist:n{#4})}
+                   {\partial #3}\l__thermodynamics_Partial_end_tl
+      }
+      { \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial #2(\__thermodynamics_sort_clist:n{#3,#4})}
+                   {\partial #3}\l__thermodynamics_Partial_end_tl
+      }
+    }
+  }
+}
+\NewDocumentCommand{\PartialBigg}{}
+  { \tl_set:Nn \l__thermodynamics_Partial_start_tl {\Biggl\l__thermodynamics_PartialOpen_tl}
+    \tl_set:Nn \l__thermodynamics_Partial_end_tl {\Biggr\l__thermodynamics_PartialClose_tl}
+    \tl_set:Nn \l__thermodynamics_Partial_Empty_end_tl
+        {\Biggr\l__thermodynamics_PartialEmptyClose_tl}
+    \Partial
+  }
+\NewDocumentCommand{\Partialbigg}{}
+  { \tl_set:Nn \l__thermodynamics_Partial_start_tl {\biggl\l__thermodynamics_PartialOpen_tl}
+    \tl_set:Nn \l__thermodynamics_Partial_end_tl {\biggr\l__thermodynamics_PartialClose_tl}
+    \tl_set:Nn \l__thermodynamics_Partial_empty_end_tl
+        {\biggr\l__thermodynamics_PartialEmptyClose_tl}
+    \Partial
+  }
+\NewDocumentCommand{\PartialSecond}{s m m m}
+{
+  \bool_if:nTF {#1}
+  {% Starred form
+    \settowidth{\l__thermodynamics_Partial_const_dim}{\ensuremath{#4}}%
+    \dim_add:Nn \l__thermodynamics_Partial_const_dim {-0.20\l__thermodynamics_Partial_const_dim}
+    \PartialSecond{#2}{#3}{#4}%
+    \bool_if:nT \l__thermodynamics_subscripted_bool
+    {  \dim_compare:nNnTF {\l__thermodynamics_operator_width_dim}
+                        < {\l__thermodynamics_Partial_const_dim}
+      { \kern -\l__thermodynamics_operator_width_dim }
+      { \kern -\l__thermodynamics_Partial_const_dim }
+    }
+  }
+  {% Unstarred form
+    \bool_if:NTF \l__thermodynamics_subscripted_bool
+    {% Handles case of empty variables held constant
+      \tl_if_eq:nnTF {#4} {}
+      { \l__thermodynamics_Partial_start_tl
+            \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2 #2}
+        {\partial #3\c_math_superscript_token 2}\l__thermodynamics_Partial_empty_end_tl
+      }
+      { \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2 #2}
+            {\partial #3\c_math_superscript_token 2}\l__thermodynamics_Partial_end_tl
+            \c_math_subscript_token{#4}%
+      }
+    }
+    {% Check whether #4 contains \allNsbut{i} and #3 is \Nt_i
+      \tl_if_in:nnTF {#2} {\Nt}
+      { \RenewDocumentCommand{\allbut}{O{j} m m}{\allcomponents{##3}}
+        \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2 #2(#4)}
+            {\partial\c_math_superscript_token 2 #3}\l__thermodynamics_Partial_end_tl
+      }
+      { \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2
+                      #2(\__thermodynamics_sort_clist:n{#3,#4})}
+            {\partial #3\c_math_superscript_token 2}\l__thermodynamics_Partial_end_tl
+      }
+    }
+  }
+}
+\NewDocumentCommand{\PartialSecondBigg}{}
+{ \tl_set:Nn \l__thermodynamics_Partial_start_tl {\biggl\l__thermodynamics_PartialOpen_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_end_tl {\biggl\l__thermodynamics_PartialClose_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_empty_end_tl {\biggl\l__thermodynamics_PartialClose_tl}
+  \PartialSecond
+}
+\NewDocumentCommand{\PartialSecondbigg}{}
+{ \tl_set:Nn \l__thermodynamics_Partial_start_tl {\biggl\l__thermodynamics_PartialOpen_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_end_tl {\biggl\l__thermodynamics_PartialClose_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_empty_end_tl {\biggl\l__thermodynamics_PartialClose_tl}
+  \PartialSecond
+}
+\bool_new:N \l__thermodynamics_has_x_or_y_bool
+\NewDocumentCommand{\PartialMixSecond}{s m m m m}
+{
+  \bool_if:nTF {#1}
+  {% Starred version
+    \settowidth{\l__thermodynamics_Partial_const_dim}{\ensuremath{#4}}%
+    \dim_add:Nn \l__thermodynamics_Partial_const_dim {-0.20\l__thermodynamics_Partial_const_dim}
+    \PartialMixSecond{#2}{#3}{#4}{#5}
+    \bool_if:nT \l__thermodynamics_subscripted_bool
+    { \dim_compare:nNnTF {\l__thermodynamics_operator_width_dim}
+                       < {\l__thermodynamics_Partial_const_dim}
+      { \kern -\l__thermodynamics_operator_width_dim }
+      { \kern -\l__thermodynamics_Partial_const_dim }
+    }
+  }
+  {% Unstarred version
+    \bool_if:nTF \l__thermodynamics_subscripted_bool
+    {% subscripted version
+      \tl_if_eq:nnTF {#5} {}
+      {% Handle case of empty variables held constant
+        \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2 #2}
+            {\partial #3\partial #4}\l__thermodynamics_Partial_empty_end_tl
+      }
+      { \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2 #2}
+            {\partial #3\partial #4}\l__thermodynamics_Partial_end_tl
+            \c_math_subscript_token{#5}
+      }
+    }
+    {% not subscripted
+      \tl_if_eq:nnTF {#5} {}
+      {% empty argument
+        \l__thermodynamics_Partial_start_tl
+        \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2
+                        #2(\__thermodynamics_sort_clist:n{#3,#4,#5})}
+                   {\partial #3\partial #4}\l__thermodynamics_Partial_empty_end_tl
+      }
+      {% Check whether #3 OR #4 are \Nt_i/etc.
+        \tl_if_in:nnTF {#3} {\Nt}
+        { \RenewDocumentCommand{\allbut}{O{j} m m}{\allcomponents{##3}}%
+          \l__thermodynamics_Partial_start_tl
+          \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2
+                        #2(\__thermodynamics_sort_clist:n{#4,#5})}
+                     {\partial #3\partial #4}\l__thermodynamics_Partial_end_tl
+        }
+        { \tl_if_in:nnTF {#4} {\Nt}
+          { \RenewDocumentCommand{\allbut}{O{j} m m}{\allcomponents{##3}}%
+            \l__thermodynamics_Partial_start_tl
+            \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2
+                            #2(\__thermodynamics_sort_clist:n{#3,#5})}
+                       {\partial #3\partial #4}\l__thermodynamics_Partial_end_tl
+          }
+          {% Check for x, y, or w
+            \bool_set_false:N \l__thermodynamics_has_x_or_y_bool
+            \tl_if_in:nnT {#3} {x}
+            { \l__thermodynamics_has_x_or_y_bool }
+            \tl_if_in:nnT {#3} {y}
+            { \l__thermodynamics_has_x_or_y_bool }
+            \tl_if_in:nnT {#3} {w}
+            { \l__thermodynamics_has_x_or_y_bool }
+            \bool_if:NTF \l__thermodynamics_has_x_or_y_bool
+            { \RenewDocumentCommand{\allbutlastand}{O{j} m m}
+                {\allcomponents{##3}}
+              \l__thermodynamics_Partial_start_tl
+              \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2
+                            #2(\__thermodynamics_sort_clist:n{#4,#5})}
+                         {\partial #3\partial #4}\l__thermodynamics_Partial_end_tl
+            }
+            {
+              \l__thermodynamics_Partial_start_tl
+              \__thermodynamics_frac:nn{\partial\c_math_superscript_token 2
+                            #2(\__thermodynamics_sort_clist:n{#3,#4,#5})}
+                         {\partial #3\partial #4}\l__thermodynamics_Partial_end_tl
+            }
+          }
+        }
+      }
+    }
+  }
+}
+\NewDocumentCommand{\PartialMixSecondBigg}{}
+{ \tl_set:Nn \l__thermodynamics_Partial_start_tl {\Biggl\l__thermodynamics_PartialOpen_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_end_tl {\Biggl\l__thermodynamics_PartialClose_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_empty_end_tl {\Biggl\l__thermodynamics_PartialClose_tl}
+  \PartialMixSecond
+}
+\NewDocumentCommand{\PartialMixSecondbigg}{}
+{ \tl_set:Nn \l__thermodynamics_Partial_start_tl {\biggl\l__thermodynamics_PartialOpen_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_end_tl {\biggl\l__thermodynamics_PartialClose_tl}
+  \tl_set:Nn \l__thermodynamics_Partial_empty_end_tl {\biggl\l__thermodynamics_PartialClose_tl}
+  \PartialMixSecond
 }
 \AtBeginDocument{%
   \@ifpackageloaded{amsmath}{}{%
       \PackageWarningNoLine{thermodynamics}
-        {Package amsmath not loaded; load to make PartialBigg and friends
-            work correctly}%
-      \let\PartialBigg\Partial
-      \let\Partialbigg\Partial
-      \let\PartialSecondBigg\PartialSecond
-      \let\PartialSecondbigg\PartialSecond
-      \let\PartialMixSecondBigg\PartialMixSecond
-      \let\PartialMixSecondbigg\PartialMixSecond
+        {Package~amsmath~not~loaded;~load~to~make~PartialBigg~and~friends
+            ~work~correctly}%
+      \cs_set_eq:NN \PartialBigg \Partial
+      \cs_set_eq:NN \Partialbigg \Partial
+      \cs_set_eq:NN \PartialSecondBigg \PartialSecond
+      \cs_set_eq:NN \PartialSecondbigg \PartialSecond
+      \cs_set_eq:NN \PartialMixSecondBigg \PartialMixSecond
+      \cs_set_eq:NN \PartialMixSecondbigg \PartialMixSecond
+      \ProvideDocumentCommand{\rvert}{}{|}
+      \ProvideDocumentCommand{\lvert}{}{|}
   }%
 }
-\newenvironment*{thermoparentheses}{
-  \renewcommand*{\PartialOpen}{(}%
-  \renewcommand*{\PartialClose}{)}%
-  \renewcommand*{\PartialEmptyClose}{)}%
+\NewDocumentCommand{\Partialinline}{}
+{
+  \cs_set:Nn \__thermodynamics_frac:nn { ##1 \l__thermodynamics_Partial_middle_tl / ##2 }
+  \Partial
+}
+\NewDocumentCommand{\PartialSecondinline}{}
+{
+  \cs_set:Nn \__thermodynamics_frac:nn { ##1 \l__thermodynamics_Partial_middle_tl / ##2 }
+  \PartialSecond
+}
+\NewDocumentCommand{\PartialMixSecondinline}{}
+{
+  \cs_set:Nn \__thermodynamics_frac:nn { ##1 \l__thermodynamics_Partial_middle_tl / ##2 }
+  \PartialMixSecond
+}
+\NewDocumentCommand{\Partialinlinetext}{}
+{ \cs_set_eq:NN \l__thermodynamics_Partial_start_tl \l__thermodynamics_PartialOpen_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_end_tl \l__thermodynamics_PartialClose_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_empty_end_tl \l__thermodynamics_PartialEmptyClose_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_middle_tl \relax
+  \Partialinline
+}
+\NewDocumentCommand{\PartialSecondinlinetext}{}
+{ \cs_set_eq:NN \l__thermodynamics_Partial_start_tl \l__thermodynamics_PartialOpen_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_end_tl \l__thermodynamics_PartialClose_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_empty_end_tl \l__thermodynamics_PartialEmptyClose_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_middle_tl \relax
+  \PartialSecondinline
+}
+\NewDocumentCommand{\PartialMixSecondinlinetext}{}
+{ \cs_set_eq:NN \l__thermodynamics_Partial_start_tl \l__thermodynamics_PartialOpen_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_end_tl \l__thermodynamics_PartialClose_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_empty_end_tl \l__thermodynamics_PartialEmptyClose_tl
+  \cs_set_eq:NN \l__thermodynamics_Partial_middle_tl \relax
+  \PartialMixSecondinline
+}
+\NewDocumentEnvironment{thermoparentheses}{}
+{ \cs_set:Nn \l__thermodynamics_PartialOpen_tl {(}
+  \cs_set:Nn \l__thermodynamics_PartialClose_tl {)}
+  \cs_set:Nn \l__thermodynamics_PartialEmptyClose_tl {)}
 }{}
-\newenvironment*{thermobrackets}{%
-  \renewcommand*{\PartialOpen}{[}%
-  \renewcommand*{\PartialClose}{]}%
-  \renewcommand*{\PartialEmptyClose}{]}%
+\NewDocumentEnvironment{thermobrackets}{}
+{ \tl_set:Nn \l__thermodynamics_PartialOpen_tl {[}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {]}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {]}
 }{}
-\newenvironment*{thermobraces}{%
-  \renewcommand*{\PartialOpen}{\{}%
-  \renewcommand*{\PartialClose}{\}}%
-  \renewcommand*{\PartialEmptyClose}{\}}%
+\NewDocumentEnvironment{thermobraces}{}
+{ \tl_set:Nn \l__thermodynamics_PartialOpen_tl {\{}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {\}}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {\}}
 }{}
-\newenvironment*{thermobar}{%
-  \renewcommand*{\PartialOpen}{.}%
-  \renewcommand*{\PartialClose}{\rvert}%
-  \renewcommand*{\PartialEmptyClose}{.}%
+\NewDocumentEnvironment{thermobar}{}
+{ \tl_set:Nn \l__thermodynamics_PartialOpen_tl {.}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {\rvert}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {.}
 }{}
-\newenvironment*{thermoplain}{%
-  \renewcommand*{\PartialOpen}{.}%
-  \renewcommand*{\PartialClose}{.}%
-  \renewcommand*{\PartialEmptyClose}{.}%
-  \@subscriptedfalse
+\NewDocumentEnvironment{thermoplain}{}
+{ \tl_set:Nn \l__thermodynamics_PartialOpen_tl {.}
+  \tl_set:Nn \l__thermodynamics_PartialClose_tl {.}
+  \tl_set:Nn \l__thermodynamics_PartialEmptyClose_tl {.}
+  \bool_set_false:N \l__thermodynamics_subscripted_bool
 }{}
-\newenvironment*{thermoNOsubscripts}{\@subscriptedfalse}{}
-\newenvironment*{thermosubscripts}{\@subscriptedtrue}{}
-\newcommand*{\DeclareSubscrSymbol}[3]{%
-  \expandafter\def\csname #1\endcsname{%
-    \@ifnextchar^{\csname @#1\endcsname}
-                 {\@ifnextchar_{\csname @@#1\endcsname}{{#2}_{#3}}}
-  }
-  \expandafter\def\csname @#1\endcsname ##1##2{%
-    {#2}^{##2}\@ifnextchar_{\csname @@@#1\endcsname}{_{#3}}%
-  }
-  \expandafter\def\csname @@#1\endcsname ##1##2{{#2}_{#3,##2}}
-  \expandafter\def\csname @@@#1\endcsname ##1##2{_{#3,##2}}
-}
-\newcommand*{\heatcapacitysymbol}{C}
-\newcommand*{\compressibilitysymbol}{\kappa}
-\newcommand*{\expansivitysymbol}{\alpha}
-\DeclareSubscrSymbol{cV}{\@intensive\heatcapacitysymbol}{\volume@symbol}
-\DeclareSubscrSymbol{cP}{\@intensive\heatcapacitysymbol}{\pressure@symbol}
-\DeclareSubscrSymbol{cVt}{\@extensive\heatcapacitysymbol}{\volume@symbol}
-\DeclareSubscrSymbol{cPt}{\@extensive\heatcapacitysymbol}{\pressure@symbol}
-\DeclareSubscrSymbol{cVs}{\@specific\heatcapacitysymbol}{\volume@symbol}
-\DeclareSubscrSymbol{cPs}{\@specific\heatcapacitysymbol}{\pressure@symbol}
-\DeclareSubscrSymbol{kappaT}{\compressibilitysymbol}{\temperature@symbol}
-\DeclareSubscrSymbol{kappaS}{\compressibilitysymbol}{\entropy@symbol}
-\DeclareSubscrSymbol{alphaP}{\expansivitysymbol}{\pressure@symbol}
-\DeclareSubscrSymbol{alphaS}{\expansivitysymbol}{\entropy@symbol}
-\newcommand*{\sat}{{\text{sat}}}
-\newcommand*{\Psat}{P^\sat}
-\let\Pvap\Psat
-\newcommand*{\phisat}{\phi^\sat}
-\newcommand*{\fsat}{f^\sat}
-\let\std\circ
-\newcommand*{\Pstd}{P^\std}
-\newcommand*{\fstd}{f^\std}
-\newcommand*{\mixing}{{\text{mix}}}
-\newcommand*{\Deltamix}[1]{\Delta{#1}_\mixing}
-\newcommand*{\fusion}{{\text{fus}}}
-\newcommand*{\reaction}{{\text{rxn}}}
-\newcommand*{\sublimation}{{\text{sub}}}
-\newcommand*{\vaporization}{{\text{vap}}}
-\newcommand*{\formation}{f}
-\newcommand*{\Deltafus}[1]{\Delta{#1}^\fusion}
-\newcommand*{\Deltasub}[1]{\Delta{#1}^\sublimation}
-\newcommand*{\Deltavap}[1]{\Delta{#1}^\vaporization}
-\let\Delta@rxn@sym\relax
-\DeclareSubscrSymbol{@DeltarxncP}{\Delta@rxn@sym}{\pressure@symbol,\reaction}
-\DeclareSubscrSymbol{@Deltarxn}{\Delta@rxn@sym}{\reaction}
-\newcommand*{\Deltarxn}[1]{%
-    \def\tmp@arg{#1}%
-    \def\tmp@@arg{\cP}%
-    \ifx\tmp@arg\tmp@@arg\relax
-      \def\@command{\def\Delta@rxn@sym{\Delta\@intensive\heatcapacitysymbol}%
-                    \@DeltarxncP}
-    \else
-      \def\@command{\def\Delta@rxn@sym{\Delta{#1}}\@Deltarxn}
-    \fi
-    \@command
-}
-\let\Delta@f@sym\relax
-\DeclareSubscrSymbol{@Deltaf}{\Delta@f@sym}{f}
-\newcommand*{\Deltaf}[1]{\def\Delta@f@sym{\Delta{#1}}\@Deltaf}
-\newcommand*{\fmix}{\hat{f}}
-\newcommand*{\phimix}{\hat\phi}
-\newcommand*{\fpure}{f}
-\let\phipure\phi
-\let\pm@symbol\relax
-\newcommand*{\partialmolar}[1]{\gdef\pm@symbol{#1}\generic@pm}
-\def\generic@pm{\@ifnextchar_\@generic@pm\@@generic@pm}
-\def\@generic@pm#1#2{%
-    \gdef\pm@arg{#2}%
-    % if nextchar after argument is ^
-    \@ifnextchar^\@@@generic@pm\@@@@generic@pm
-}
-\def\@@@generic@pm#1#2{\thermo@overline{\pm@symbol^{#2}_{\pm@arg}}}
-\def\@@@@generic@pm{\thermo@overline{\pm@symbol_{\pm@arg}}}
-\def\@@generic@pm{\@ifnextchar^\@@@@@generic@pm\@pm@bracket@check}
-\def\@@@@@generic@pm#1#2#3#4{\thermo@overline{\pm@symbol^{#2}_{#4}}}
-\def\@pm@bracket@check{\@ifnextchar[\@pm@bracket@yes\@pm@bracket@no}
-\def\@pm@bracket@yes[#1]#2{\thermo@overline{\pm@symbol^{#1}_{#2}}}
-\def\@pm@bracket@no#1{\thermo@overline{\pm@symbol_{#1}}}
-\newcommand*{\Nt}{\mole@symbol}
-\newcommand*{\Et}{\@extensive\totalenergy@symbol}
-\newcommand*{\Ut}{\@extensive\internalenergy@symbol}
-\newcommand*{\Ft}{\@extensive\Helmholtz@symbol}
-\newcommand*{\Gt}{\@extensive\Gibbs@symbol}
-\newcommand*{\Ht}{\@extensive\enthalpy@symbol}
-\newcommand*{\Lt}{\@extensive\Landau@symbol}
-\newcommand*{\At}{\@extensive\area@symbol}
-\newcommand*{\St}{\@extensive\entropy@symbol}
-\newcommand*{\Vt}{\@extensive\volume@symbol}
-\newcommand*{\Qt}{\@extensive\heat@symbol}
-\newcommand*{\Wt}{\@extensive\work@symbol}
-\newcommand*{\Mt}{\@extensive M}
-\newcommand*{\Bt}{\@extensive B}
-\newcommand*{\Em}{\@intensive\totalenergy@symbol}
-\newcommand*{\Um}{\@intensive\internalenergy@symbol}
-\newcommand*{\Fm}{\@intensive\Helmholtz@symbol}
-\newcommand*{\Gm}{\@intensive\Gibbs@symbol}
-\newcommand*{\Hm}{\@intensive\enthalpy@symbol}
-\newcommand*{\Lm}{\@intensive\Landau@symbol}
-\newcommand*{\Am}{\@intensive\area@symbol}
-\newcommand*{\Sm}{\@intensive\entropy@symbol}
-\newcommand*{\Vm}{\@intensive\volume@symbol}
-\newcommand*{\Qm}{\@intensive\heat@symbol}
-\newcommand*{\Wm}{\@intensive\work@symbol}
-\newcommand*{\Mm}{\@intensive M}
-\newcommand*{\Bm}{\@intensive B}
-\newcommand*{\Us}{\@specific\internalenergy@symbol}
-\newcommand*{\Es}{\@specific\totalenergy@symbol}
-\newcommand*{\Fs}{\@specific\Helmholtz@symbol}
-\newcommand*{\Gs}{\@specific\Gibbs@symbol}
-\newcommand*{\Hs}{\@specific\enthalpy@symbol}
-\newcommand*{\Ls}{\@specific\Landau@symbol}
-\newcommand*{\As}{\@specific\area@symbol}
-\newcommand*{\Ss}{\@specific\entropy@symbol}
-\newcommand*{\Vs}{\@specific\volume@symbol}
-\newcommand*{\Qs}{\@specific\heat@symbol}
-\newcommand*{\Ws}{\@specific\work@symbol}
-\newcommand*{\Ms}{\@specific M}
-\newcommand*{\Bs}{\@specific B}
-\newcommand*{\Epm}{\partialmolar{\totalenergy@symbol}}
-\newcommand*{\Upm}{\partialmolar{\internalenergy@symbol}}
-\newcommand*{\Hpm}{\partialmolar{\enthalpy@symbol}}
-\newcommand*{\Fpm}{\partialmolar{\Helmholtz@symbol}}
-\newcommand*{\Gpm}{\partialmolar{\Gibbs@symbol}}
-\newcommand*{\Apm}{\partialmolar{\area@symbol}}
-\newcommand*{\Spm}{\partialmolar{\entropy@symbol}}
-\newcommand*{\Vpm}{\partialmolar{\volume@symbol}}
-\newcommand*{\Lpm}{\partialmolar{\Omega}}
-\newcommand*{\Mpm}{\partialmolar{M}}
-\newcommand*{\Bpm}{\partialmolar{B}}
-\newcommand*{\cPpm}{%
-  \def\@@@generic@pm##1##2{%
-    \thermo@overline{\pm@symbol^{##2}_{\pressure@symbol,\pm@arg}}}%
-  \def\@@@@generic@pm{\thermo@overline{\pm@symbol_{\pressure@symbol,\pm@arg}}}%
-  \def\@@@@@generic@pm##1##2##3##4{%
-    \thermo@overline{\pm@symbol^{##2}_{\pressure@symbol,##4}}}%
-  \def\@pm@bracket@yes[##1]##2{%
-    \thermo@overline{\pm@symbol^{##1}_{\pressure@symbol,##2}}}%
-  \def\@pm@bracket@no##1{\thermo@overline{\pm@symbol_{\pressure@symbol,##1}}}%
-  \partialmolar{\heatcapacitysymbol}%
-}
-\newcommand*{\cVpm}{%
-  \def\@@@generic@pm##1##2{%
-    \thermo@overline{\pm@symbol^{##2}_{\volume@symbol,\pm@arg}}}%
-  \def\@@@@generic@pm{\thermo@overline{\pm@symbol_{\volume@symbol,\pm@arg}}}%
-  \def\@@@@@generic@pm##1##2##3##4{%
-    \thermo@overline{\pm@symbol^{##2}_{\volume@symbol,##4}}}%
-  \def\@pm@bracket@yes[##1]##2{%
-    \thermo@overline{\pm@symbol^{##1}_{\volume@symbol,##2}}}%
-  \def\@pm@bracket@no##1{\thermo@overline{\pm@symbol_{\volume@symbol,##1}}}%
-  \partialmolar{\heatcapacitysymbol}%
-}
-\newcommand*{\residual}{R}
-\newcommand*{\excess}{E}
-\newcommand*{\UR}{\Um^\residual}
-\newcommand*{\HR}{\Hm^\residual}
-\newcommand*{\FR}{\Fm^\residual}
-\newcommand*{\GR}{\Gm^\residual}
-\newcommand*{\VR}{\Vm^\residual}
-\newcommand*{\SR}{\Sm^\residual}
-\newcommand*{\URt}{\Ut^\residual}
-\newcommand*{\HRt}{\Ht^\residual}
-\newcommand*{\FRt}{\Ft^\residual}
-\newcommand*{\GRt}{\Gt^\residual}
-\newcommand*{\VRt}{\Vt^\residual}
-\newcommand*{\SRt}{\St^\residual}
-\newcommand*{\URs}{\Us^\residual}
-\newcommand*{\HRs}{\Hs^\residual}
-\newcommand*{\FRs}{\Fs^\residual}
-\newcommand*{\GRs}{\Gs^\residual}
-\newcommand*{\VRs}{\Vs^\residual}
-\newcommand*{\SRs}{\Ss^\residual}
-\newcommand*{\URpm}{\partialmolar{\internalenergy@symbol^\residual}}
-\newcommand*{\HRpm}{\partialmolar{\enthalpy@symbol^\residual}}
-\newcommand*{\FRpm}{\partialmolar{\Helmholtz@symbol^\residual}}
-\newcommand*{\GRpm}{\partialmolar{\Gibbs@symbol^\residual}}
-\newcommand*{\VRpm}{\partialmolar{\volume@symbol^\residual}}
-\newcommand*{\SRpm}{\partialmolar{\entropy@symbol^\residual}}
-\newcommand*{\UE}{\Um^\excess}
-\newcommand*{\FE}{\Fm^\excess}
-\newcommand*{\HE}{\Hm^\excess}
-\newcommand*{\GE}{\Gm^\excess}
-\newcommand*{\SE}{\Sm^\excess}
-\newcommand*{\VE}{\Vm^\excess}
-\newcommand*{\UEt}{\Ut^\excess}
-\newcommand*{\FEt}{\Ft^\excess}
-\newcommand*{\HEt}{\Ht^\excess}
-\newcommand*{\GEt}{\Gt^\excess}
-\newcommand*{\SEt}{\St^\excess}
-\newcommand*{\VEt}{\Vt^\excess}
-\newcommand*{\UEs}{\Us^\excess}
-\newcommand*{\FEs}{\Fs^\excess}
-\newcommand*{\HEs}{\Hs^\excess}
-\newcommand*{\GEs}{\Gs^\excess}
-\newcommand*{\SEs}{\Ss^\excess}
-\newcommand*{\VEs}{\Vs^\excess}
-\newcommand*{\UEpm}{\partialmolar{\internalenergy@symbol^\excess}}
-\newcommand*{\HEpm}{\partialmolar{\enthalpy@symbol^\excess}}
-\newcommand*{\FEpm}{\partialmolar{\Helmholtz@symbol^\excess}}
-\newcommand*{\GEpm}{\partialmolar{\Gibbs@symbol^\excess}}
-\newcommand*{\VEpm}{\partialmolar{\volume@symbol^\excess}}
-\newcommand*{\SEpm}{\partialmolar{\entropy@symbol^\excess}}
-\newcommand*{\sumall}{\@ifnextchar_\@sumall\@@sumall}
-\def\@sumall#1#2{\sum_{#2=1}^{\ncomponents}}
-\def\@@sumall#1{\sum_{#1=1}^{\ncomponents}}
-\newcommand*{\sumallbutlast}{\@ifnextchar_\@sumallbutlast\@@sumallbutlast}
-\def\@sumallbutlast#1#2{\sum_{#2=1}^{\ncomponents-1}}
-\def\@@sumallbutlast#1{\sum_{#1=1}^{\ncomponents-1}}
-\newcommand*{\prodall}{\@ifnextchar_\@prodall\@@prodall}
-\def\@prodall#1#2{\prod_{#2=1}^{\ncomponents}}
-\def\@@prodall#1{\prod_{#1=1}^{\ncomponents}}
-\newcommand*{\IG}{{\text{IG}}}
-\newcommand*{\IGM}{{\text{IGM}}}
-\newcommand*{\IS}{{\text{IS}}}
-\newcommand*{\Henryrat}{h}
-\newcommand*{\Henrymol}{{\mathcal{H}}}
+\NewDocumentEnvironment{thermoNOsubscripts}{}
+    {\bool_set_false:N \l__thermodynamics_subscripted_bool}
+    {}
+\NewDocumentEnvironment{thermosubscripts}{}
+    {\bool_set_true:N \l__thermodynamics_subscripted_bool}
+    {}
+\NewDocumentEnvironment{thermomolesrange}{}
+    { \__thermodynamics_set_moles_range }
+    {}
+\NewDocumentEnvironment{thermointensiveplain}{}
+    { \__thermodynamics_set_intensive_plain }
+    {}
+\NewDocumentEnvironment{thermoextensiveplain}{}
+    { \__thermodynamics_set_extensive_plain }
+    {}
+\NewDocumentEnvironment{thermointensivelowercase}{}
+    {% {
+
+      \__thermodynamics_set_intensive_lowercase
+      \__thermodynamics_set_lowercase_pms
+    }
+    {}
+\NewDocumentEnvironment{thermoextensivesuperscript}{}
+    {
+      \__thermodynamics_set_extensive_superscripts
+    }
+    {}
+\cs_new:Npn \__thermodynamics_check_definable:nN #1#2
+{
+  \bool_set_true:N \l__thermodynamics_arg_legal_bool
+  \tl_trim_spaces_apply:nN {#1} \tl_if_single_token:nTF
+  {
+    \str_set:Nx \l_tmp_str {\tl_to_str:n {#1}}
+    \int_compare:nNnT {\str_count:N \l_tmp_str} = 1
+    { \PackageError{thermodynamics}
+        {First~argument~of~'\tl_trim_spaces:o {\tl_to_str:n {#2}}'~
+         must~be~a~command}
+        {The~first~argument~of~'\tl_trim_spaces:o {\tl_to_str:n {#2}}'~
+         should~be~the~macro~that~will~be~used~to~refer~to~the~symbol.~
+         The~provided~argument~'\tl_trim_spaces:o {\tl_to_str:n {#1}}'~
+         is~a~single~character.
+         \MessageBreak Perhaps~a~backslash~is~missing?}
+    }
+  }
+  { \PackageError{thermodynamics}
+      {First~argument~of~'\tl_trim_spaces:o {\tl_to_str:n {#2}}'~
+       must~be~a~command}
+      {The~first~argument~of~'\tl_trim_spaces:o {\tl_to_str:n {#2}}'~
+       should~be~the~macro~that~will~be~used~to~refer~to~the~symbol.~
+       The~provided~argument~'\tl_trim_spaces:o {\tl_to_str:n {#1}}'~
+       contains~more~than~one~token.
+       \MessageBreak Perhaps~a~backslash~is~missing?}
+  }
+}
+\NewDocumentCommand{\NewSubscriptedSymbol}{m m m}
+{
+  \__thermodynamics_check_definable:nN {#1} \NewSubscriptedSymbol
+  \cs_if_exist:NT #1
+  { \PackageError{thermodynamics}
+      {Command~'\tl_trim_spaces:o {\tl_to_str:n {#1}}'~already~defined}
+      {You~have~used~
+       '\tl_trim_spaces:o {\tl_to_str:n {\NewSubscriptedSymbol}}'~
+       with~a~command~that~already~has~a~definition}
+  }
+  \cs_new:cpn {\cs_to_str:N #1_one:n} ##1
+  {
+    {#2}\c_math_superscript_token{##1}
+    \peek_catcode_remove:NTF \c_math_subscript_token
+    { \use:c {\cs_to_str:N #1_three:n} }
+    { \c_math_subscript_token{#3} }
+  }
+
+  \cs_new:cpn {\cs_to_str:N #1_two:n} ##1
+  { {#2}\c_math_subscript_token{#3,##1} }
+
+  \cs_new:cpn {\cs_to_str:N #1_three:n} ##1
+  { \c_math_subscript_token{#3,##1} }
+
+  \NewDocumentCommand{#1}{}
+  {% @branch
+    \peek_catcode_remove:NTF \c_math_superscript_token
+    { \use:c {\cs_to_str:N #1_one:n} }
+    { \peek_catcode_remove:NTF \c_math_subscript_token
+      { \use:c {\cs_to_str:N #1_two:n} }
+      { {#2}\c_math_subscript_token{#3} }
+    }
+  }
+}
+\NewDocumentCommand{\RenewSubscriptedSymbol}{m m m}
+{
+  \__thermodynamics_check_definable:nN {#1} \RenewSubscriptedSymbol
+  \cs_if_exist:NF #1
+  { \PackageError{thermodynamics}
+      {Command~'\tl_trim_spaces:o {\tl_to_str:n {#1}}'~not~defined}
+      {You~have~used~
+       '\tl_trim_spaces:o {\tl_to_str:n {\RenewSubscriptedSymbol}}'~
+       with~a~command~that~does~not~have~a~definition}
+  }
+  \cs_set:cpn {\cs_to_str:N #1_one:n} ##1
+  {
+    {#2}\c_math_superscript_token{##1}
+    \peek_catcode_remove:NTF \c_math_subscript_token
+    { \use:c {\cs_to_str:N #1_three:n} }
+    { \c_math_subscript_token{#3} }
+  }
+
+  \cs_set:cpn {\cs_to_str:N #1_two:n} ##1
+  { {#2}\c_math_subscript_token{#3,##1} }
+
+  \cs_set:cpn {\cs_to_str:N #1_three:n} ##1
+  { \c_math_subscript_token{#3,##1} }
+
+  \RenewDocumentCommand{#1}{}
+  {% @branch
+    \peek_catcode_remove:NTF \c_math_superscript_token
+    { \use:c {\cs_to_str:N #1_one:n} }
+    { \peek_catcode_remove:NTF \c_math_subscript_token
+      { \use:c {\cs_to_str:N #1_two:n} }
+      { {#2}\c_math_subscript_token{#3} }
+    }
+  }
+
+}
+\NewDocumentCommand{\NewSuperscriptedSymbol}{m m m}
+{
+  \__thermodynamics_check_definable:nN {#1} \NewSuperscriptedSymbol
+  \cs_if_exist:NT #1
+  { \PackageError{thermodynamics}
+      {Command~'\tl_trim_spaces:o {\tl_to_str:n {#1}}'~already~defined}
+      {You~have~used~
+       '\tl_trim_spaces:o {\tl_to_str:n {\NewSuperscriptedSymbol}}'~
+       with~a~command~that~already~has~a~definition}
+  }
+  \cs_new:cpn {\cs_to_str:N #1_one:n} ##1
+  {
+    {#2}\c_math_subscript_token{#1}
+    \peek_catcode_remove:NTF \c_math_superscript_token
+    { \use:c {\cs_to_str:N #1_one:n} }
+    { \c_math_subscript_token{#3} }
+  }
+
+  \cs_new:cpn {\cs_to_str:N #1_two:n} ##1
+  { {#2}\c_math_superscript_token{#3,##1} }
+
+  \cs_new:cpn {\cs_to_str:N #1_three:n} ##1
+  { {#2}\c_math_superscript_token{#3,##1} }
+
+  \NewDocumentCommand{#1}{}
+  {
+    \peek_catcode_remove:NTF \c_math_subscript_token
+    { \use:c {\cs_to_str:N #1_one:n} }
+    { \peek_catcode_remove:NTF \c_math_superscript_token
+      { \use:c {\cs_to_str:N #1_two:n} }
+      { {#2}\c_math_superscript_token{#3} }
+    }
+  }
+}
+\NewDocumentCommand{\RenewSuperscriptedSymbol}{m m m}
+{
+  \__thermodynamics_check_definable:nN {#1} \RenewSuperscriptedSymbol
+  \cs_if_exist:NF #1
+  { \PackageError{thermodynamics}
+      {Command~'\tl_trim_spaces:o {\tl_to_str:n {#1}}'~not~defined}
+      {You~have~used~
+       '\tl_trim_spaces:o {\tl_to_str:n {\RenewSuperscriptedSymbol}}'~
+       with~a~command~that~does~not~have~a~definition}
+  }
+  \cs_set:cpn {\cs_to_str:N #1_one:n} ##1
+  {
+    {#2}\c_math_subscript_token{##1}
+    \peek_catcode_remove:NTF \c_math_superscript_token
+    { \use:c {\cs_to_str:N #1_three:n} }
+    { \c_math_superscript_token{#3} }
+  }
+
+  \cs_set:cpn {\cs_to_str:N #1_two:n} ##1
+  { {#2}\c_math_superscript_token{#3,##1} }
+
+  \cs_set:cpn {\cs_to_str:N #1_three:n} ##1
+  { \c_math_superscript_token{#3,##1} }
+
+  \RenewDocumentCommand{#1}{}
+  {% @branch
+    \peek_catcode_remove:NTF \c_math_subscript_token
+    { \use:c {\cs_to_str:N #1_one:n} }
+    { \peek_catcode_remove:NTF \c_math_superscript_token
+      { \use:c {\cs_to_str:N #1_two:n} }
+      { {#2}\c_math_superscript_token{#3} }
+    }
+  }
+}
+\NewExpandableDocumentCommand{\heatcapacitysymbol}{}{C}
+\NewExpandableDocumentCommand{\compressibilitysymbol}{}{\kappa}
+\NewExpandableDocumentCommand{\expansivitysymbol}{}{\alpha}
+\NewExpandableDocumentCommand{\JTsymbol}{}{\mu}
+\NewSubscriptedSymbol{\cV}{\__thermodynamics_intensive:n \heatcapacitysymbol}
+    {\g__thermodynamics_volume_symbol}
+\NewSubscriptedSymbol{\cP}{\__thermodynamics_intensive:n \heatcapacitysymbol}
+    {\g__thermodynamics_pressure_symbol}
+\NewSubscriptedSymbol{\cVt}{\__thermodynamics_extensive:n \heatcapacitysymbol}
+    {\g__thermodynamics_volume_symbol}
+\NewSubscriptedSymbol{\cPt}{\__thermodynamics_extensive:n \heatcapacitysymbol}
+    {\g__thermodynamics_pressure_symbol}
+\NewSubscriptedSymbol{\cVs}{\__thermodynamics_specific:n \heatcapacitysymbol}
+    {\g__thermodynamics_volume_symbol}
+\NewSubscriptedSymbol{\cPs}{\__thermodynamics_specific:n \heatcapacitysymbol}
+    {\g__thermodynamics_pressure_symbol}
+\NewSubscriptedSymbol{\kappaT}{\compressibilitysymbol}
+    {\g__thermodynamics_temperature_symbol}
+\NewSubscriptedSymbol{\kappaS}{\compressibilitysymbol}
+    {\g__thermodynamics_entropy_symbol}
+\NewSubscriptedSymbol{\alphaP}{\expansivitysymbol}{\g__thermodynamics_pressure_symbol}
+\NewSubscriptedSymbol{\alphaS}{\expansivitysymbol}{\g__thermodynamics_entropy_symbol}
+\NewSubscriptedSymbol{\muJT}{\JTsymbol}{JT}
+\NewDocumentCommand{\sat}{}{{\text{sat}}}
+\NewDocumentCommand{\Psat}{}{P\c_math_superscript_token\sat}
+\NewDocumentCommand{\Pvap}{}{\Psat}
+\NewDocumentCommand{\phisat}{}{\phi\c_math_superscript_token\sat}
+\NewDocumentCommand{\fsat}{}{\fpure\c_math_superscript_token\sat}
+\NewDocumentCommand{\std}{}{\circ}
+\NewDocumentCommand{\Pstd}{}{P\c_math_superscript_token \std}
+\NewDocumentCommand{\fstd}{}{f\c_math_superscript_token \std}
+\NewDocumentCommand{\mixing}{}{{\text{mix}}}
+\NewDocumentCommand{\Deltamix}{m}
+    {\Delta{#1}\c_math_subscript_token\mixing}
+\NewDocumentCommand{\fusion}{}{{\text{fus}}}
+\NewDocumentCommand{\reaction}{}{{\text{rxn}}}
+\NewDocumentCommand{\sublimation}{}{{\text{sub}}}
+\NewDocumentCommand{\vaporization}{}{{\text{vap}}}
+\NewDocumentCommand{\formation}{}{f}
+\NewDocumentCommand{\Deltafus}{m}
+    {\Delta #1\c_math_superscript_token\fusion}
+\NewDocumentCommand{\Deltasub}{m}
+    {\Delta #1\c_math_superscript_token\sublimation}
+\NewDocumentCommand{\Deltavap}{m}
+    {\Delta #1\c_math_superscript_token\vaporization}
+\NewDocumentCommand{\Deltarxn}{m}
+    {\Delta #1\c_math_subscript_token\reaction}
+\tl_new:N \l__thermodynamics_Deltaf_sym_tl
+\NewSubscriptedSymbol{\__thermodynamics_Deltaf}{\l__thermodynamics_Deltaf_sym_tl}{f}
+\NewDocumentCommand{\Deltaf}{m}
+{ \tl_set:Nn \l__thermodynamics_Deltaf_sym_tl {\Delta #1}
+  \__thermodynamics_Deltaf
+}
+\NewDocumentCommand{\fmix}{}{\hat{f}}
+\NewDocumentCommand{\phimix}{}{\hat\phi}
+\NewDocumentCommand{\fpure}{}{f}
+\NewDocumentCommand{\phipure}{}{\phi}
+\tl_new:N \l__thermodynamics_pm_symbol_tl
+\tl_new:N \l__thermodynamics_pm_arg_tl
+\NewDocumentCommand{\partialmolar}{m}
+{
+  \tl_set:Nn \l__thermodynamics_pm_symbol_tl {#1}
+  \__thermodynamics_generic_pm:
+}
+%% cases to consider:
+%% (1) \Mpm{i}
+%% (2) \Mpm[S]{i}
+%% (3) \Mpm^S_i
+%% (4) \Mpm_i^S
+%% (5) \Mpm_i
+%% note that \Mpm^S with no subscript makes no sense and is thus forbidden
+\cs_new:Nn \__thermodynamics_generic_pm:
+{
+  \peek_catcode_remove:NTF \c_math_subscript_token
+  {% case 4 or case 5
+    \__thermodynamics_pm_case_four_or_five
+  }
+  {% look for superscript token
+    \peek_catcode_remove:NTF \c_math_superscript_token
+    {% case 3: \Mpm^{#1}_{#2} or \Mpm^{#1}{#2}
+      \__thermodynamics_pm_case_three
+    }
+    {% Look for optional argument [...]
+      \peek_charcode:NTF [
+      {% case 2: \Mpm[S]{i}
+        \__thermodynamics_pm_case_two
+      }
+      {% case 1: \Mpm{i}
+        \__thermodynamics_pm_case_one
+      }
+    }
+  }
+}
+\cs_new:Npn \__thermodynamics_pm_case_one #1
+{
+  \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_subscript_token{#1}}
+}
+\cs_new:Npn \__thermodynamics_pm_case_two [#1]#2
+{
+  \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+    \c_math_superscript_token{#1}\c_math_subscript_token{#2}}
+}
+\cs_new:Npn \__thermodynamics_pm_case_three #1
+{
+  \tl_set:Nn \l__thermodynamics_pm_arg_tl {#1}
+  \peek_catcode_remove:NTF \c_math_subscript_token
+  { \__thermodynamics_pm_case_three_part_two }
+  { \__thermodynamics_pm_case_three_part_two }
+}
+\cs_new:Npn \__thermodynamics_pm_case_three_part_two #1
+{
+  \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+    \c_math_superscript_token{\l__thermodynamics_pm_arg_tl}
+    \c_math_subscript_token{#1}}
+}
+\cs_new:Npn \__thermodynamics_pm_case_four_or_five #1
+{
+  \tl_set:Nn \l__thermodynamics_pm_arg_tl {#1}
+  \peek_catcode_remove:NTF \c_math_superscript_token
+  { \__thermodynamics_pm_case_four }
+  { \__thermodynamics_pm_case_five }
+}
+\cs_new:Npn \__thermodynamics_pm_case_four #1
+{
+  \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_superscript_token{#1}
+    \c_math_subscript_token{\l__thermodynamics_pm_arg_tl}}
+}
+\cs_new:Npn \__thermodynamics_pm_case_five
+{
+  \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+    \c_math_subscript_token{\l__thermodynamics_pm_arg_tl}}
+}
+\NewDocumentCommand{\NewThermodynamicProperty}{m m}
+{
+  \NewExtensiveProperty{#1}{#2}
+  \NewPartialMolarProperty{#1}{#2}
+  \NewResidualProperty{#1}{#2}
+  \NewExcessProperty{#1}{#2}
+}
+\NewDocumentCommand{\NewExtensiveProperty}{m m}
+{
+  % Extensive property
+  \exp_after:wN \NewDocumentCommand \exp_after:wN
+    {\cs:w #1t\cs_end:}{}{\__thermodynamics_extensive:n {#2}}
+  % Molar property
+  \exp_after:wN \NewDocumentCommand \exp_after:wN
+    {\cs:w #1m\cs_end:}{}{\__thermodynamics_intensive:n {#2}}
+  % Specific property
+  \exp_after:wN \NewDocumentCommand \exp_after:wN
+    {\cs:w #1s\cs_end:}{}{\__thermodynamics_specific:n {#2}}
+}
+\NewDocumentCommand{\NewPartialMolarProperty}{m m}
+{
+  % Partial molar property
+  \exp_after:wN \NewDocumentCommand \exp_after:wN
+    {\cs:w #1pm\cs_end:}{}{\partialmolar{#2}}
+}
+\NewDocumentCommand{\NewExcessProperty}{m m}
+{
+  \exp_after:wN \NewSuperscriptedSymbol \exp_after:wN
+    {\cs:w #1 Et\cs_end:}{\__thermodynamics_extensive:n{#2}}{\excess}
+  \exp_after:wN \NewSuperscriptedSymbol \exp_after:wN
+    {\cs:w #1 E\cs_end:}{\__thermodynamics_intensive:n{#2}}{\excess}
+  \exp_after:wN \NewSuperscriptedSymbol \exp_after:wN
+    {\cs:w #1 Es\cs_end:}{\__thermodynamics_specific:n{#2}}{\excess}
+
+  %^^A TODO: make super- or subscripted partial molar quantities work
+  % Excess partial molar property
+  \exp_after:wN \NewDocumentCommand \exp_after:wN
+    {\cs:w #1Epm\cs_end:}{}{\partialmolar{#2}
+       \c_math_superscript_token\excess}
+}
+\NewDocumentCommand{\NewResidualProperty}{m m}
+{
+  \exp_after:wN \NewSuperscriptedSymbol \exp_after:wN
+    {\cs:w #1 Rt\cs_end:}{\__thermodynamics_extensive:n{#2}}{\residual}
+  \exp_after:wN \NewSuperscriptedSymbol \exp_after:wN
+    {\cs:w #1 R\cs_end:}{\__thermodynamics_intensive:n{#2}}{\residual}
+  \exp_after:wN \NewSuperscriptedSymbol \exp_after:wN
+    {\cs:w #1 Rs\cs_end:}{\__thermodynamics_specific:n{#2}}{\residual}
+
+  % Residual partial molar property
+  \exp_after:wN \NewDocumentCommand \exp_after:wN
+    {\cs:w #1Rpm\cs_end:}{}{\partialmolar{#2}
+        \c_math_superscript_token\residual}
+}
+\NewDocumentCommand{\Nt}{}{\g__thermodynamics_mole_symbol}
+\NewThermodynamicProperty{E}{\g__thermodynamics_total_energy_symbol}
+\NewThermodynamicProperty{U}{\g__thermodynamics_internal_energy_symbol}
+\NewThermodynamicProperty{F}{\g__thermodynamics_Helmholtz_symbol}
+\NewThermodynamicProperty{G}{\g__thermodynamics_Gibbs_symbol}
+\NewThermodynamicProperty{H}{\g__thermodynamics_enthalpy_symbol}
+\NewThermodynamicProperty{L}{\g__thermodynamics_Landau_symbol}
+\NewThermodynamicProperty{V}{\g__thermodynamics_volume_symbol}
+\NewThermodynamicProperty{S}{\g__thermodynamics_entropy_symbol}
+\NewExtensiveProperty{A}{\g__thermodynamics_area_symbol}
+\NewPartialMolarProperty{A}{\g__thermodynamics_area_symbol}
+\NewExtensiveProperty{Q}{\g__thermodynamics_heat_symbol}
+\NewExtensiveProperty{W}{\g__thermodynamics_work_symbol}
+\NewDocumentCommand{\cPpm}{}
+{
+  \cs_set:Npn \__thermodynamics_pm_case_one ##1
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_subscript_token
+        {\g__thermodynamics_pressure_symbol,##1}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_two [##1]##2
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_superscript_token{##1}
+        \c_math_subscript_token{\g__thermodynamics_pressure_symbol,##2}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_three_part_two ##1
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+        \c_math_superscript_token{\l__thermodynamics_pm_arg_tl}
+        \c_math_subscript_token{\g__thermodynamics_pressure_symbol,##1}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_four ##1
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+        \c_math_superscript_token{##1}\c_math_subscript_token
+      {\g__thermodynamics_pressure_symbol,\l__thermodynamics_pm_arg_tl}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_five
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_subscript_token
+        {\g__thermodynamics_pressure_symbol,\l__thermodynamics_pm_arg_tl}}
+  }
+  \partialmolar{\heatcapacitysymbol}
+}
+\NewDocumentCommand{\cVpm}{}
+{
+  \cs_set:Npn \__thermodynamics_pm_case_one ##1
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_subscript_token
+        {\g__thermodynamics_volume_symbol,##1}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_two [##1]##2
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+            \c_math_superscript_token{##1}\c_math_subscript_token
+        {\g__thermodynamics_volume_symbol,##2}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_three_part_two ##1
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+        \c_math_superscript_token{\l__thermodynamics_pm_arg_tl}
+        \c_math_subscript_token{\g__thermodynamics_volume_symbol,##1}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_four ##1
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl
+        \c_math_superscript_token{##1}
+        \c_math_subscript_token
+      {\g__thermodynamics_volume_symbol,\l__thermodynamics_pm_arg_tl}}
+  }
+  \cs_set:Npn \__thermodynamics_pm_case_five
+  {
+    \__thermodynamics_overline:n {\l__thermodynamics_pm_symbol_tl\c_math_subscript_token
+        {\g__thermodynamics_volume_symbol,\l__thermodynamics_pm_arg_tl}}
+  }
+  \partialmolar{\heatcapacitysymbol}
+}
+\NewDocumentCommand{\residual}{}{R}
+\NewDocumentCommand{\excess}{}{E}
+\NewDocumentCommand{\sumall}{m m}
+  { \sum\c_math_subscript_token{#2=1}
+      \c_math_superscript_token{\ncomponents} }
+\NewDocumentCommand{\sumallbutlast}{m m}
+  { \sum\c_math_subscript_token{#2=1}
+      \c_math_superscript_token{\ncomponents-1} }
+\NewDocumentCommand{\prodall}{m m}
+  { \prod\c_math_subscript_token{#2=1}
+       \c_math_superscript_token{\ncomponents} }
+\NewDocumentCommand{\IG}{}{{\text{IG}}}
+\NewDocumentCommand{\IGM}{}{{\text{IGM}}}
+\NewDocumentCommand{\IS}{}{{\text{IS}}}
+\NewDocumentCommand{\Henryrat}{}{h}
+\NewDocumentCommand{\Henrymol}{}{\mathcal{H}}
 \AtBeginDocument{%
   \providecommand*{\square}{%
     \text{\leavevmode
-      \hbox to.77778em{%
+      \hbox to.65em{%
       \hfil\vrule
-      \vbox to.6em{\hrule width.6em\vfil\hrule}%
+      \vbox to.53em{\hrule width.45em\vfil\hrule}%
       \vrule\hfil}%
     }%
   }%
 }
-\newcommand*{\gammarat}{\gamma^\ast}
-\newcommand*{\gammamol}{\gamma^\square}
-\newcommand*{\Jacobian}[4]{\frac{\partial{(#1,#2)}}{\partial{(#3,#4)}}}%
+\NewDocumentCommand{\gammarat}{}{\gamma\c_math_superscript_token\ast}
+\NewDocumentCommand{\gammamol}{}{\gamma\c_math_superscript_token\square}
+\NewDocumentEnvironment{thermovmatrix}{}
+{ \cs_if_exist:NTF \vmatrix
+  { \begin{vmatrix} }
+  { \left|\begin{array}{c c c c c c c c c c} }
+}
+{ \cs_if_exist:NTF \endvmatrix
+  {  \end{vmatrix} }
+  {  \end{array}\right| }
+}
+\NewDocumentCommand{\Jacobian}{m m}
+    {\__thermodynamics_frac:nn{\partial(#1)}{\partial{(#2)}}}
+\NewDocumentCommand{\Jacobiandet}{O{} O{} m m}
+{
+  \__thermodynamics_Jacobian_set_ncomponents:nn {#3} {#4}
+  \begin{thermovmatrix}
+    \__thermodynamics_Jacobianmatrix:nnnn {#1} {#2} {#3} {#4}
+  \end{thermovmatrix}
+}
+\seq_new:N \l__thermodynamics_row_seq
+\seq_new:N \l__thermodynamics_matrix_seq
+\clist_new:N \l__thermodynamics_other_vars_clist
+\clist_new:N \l__thermodynamics_other_vars_copy_clist
+\tl_new:N \l__thermodynamics_Jacobian_x_tl
+\tl_new:N \l__thermodynamics_Jacobian_n_tl
+\tl_new:N \l__thermodynamics_Jacobian_temp_tl
+\bool_new:N \l__thermodynamics_found_dots_bool
+\cs_new:Nn \__thermodynamics_Jacobian_set_ncomponents:nn
+{
+  % If any entry is \dots, we assume the Jacobian is of the form
+  % d(f_1,\dots,f_n)/d(x_1,\dots,x_n) where f is some function
+  % (any symbol) and x is some variable (any symbol).
+  \tl_if_in:nnTF {#1} {\dots}
+  {% Has dots
+    \bool_set_true:N \l__thermodynamics_found_dots_bool
+    % look for what "x" is
+    \tl_set:Nn \l__thermodynamics_Jacobian_x_tl {\tl_head:n {#2}}
+    % look for what "n" is and set \ncomponents to it
+    \tl_set:Nx \l__thermodynamics_Jacobian_n_tl {\tl_item:nn {#2} {-1}}
+    \RenewExpandableDocumentCommand{\ncomponents}{}{\l__thermodynamics_Jacobian_n_tl}
+  }
+  {% Does not have dots; proceed accordingly
+    \bool_set_false:N \l__thermodynamics_found_dots_bool
+  }
+}
+\cs_new_protected:Nn \__thermodynamics_Jacobianmatrix:nnnn
+{
+  \seq_clear:N \l__thermodynamics_matrix_seq
+  \clist_set:Nn \l__thermodynamics_other_vars_clist {#4}
+  \clist_set_eq:NN \l__thermodynamics_other_vars_copy_clist \l__thermodynamics_other_vars_clist
+
+  \clist_map_inline:nn {#3}
+  {
+    \seq_clear:N \l__thermodynamics_row_seq
+    \tl_if_in:nnTF {##1} {\dots}
+    {% The current row has "dots" => row is \vdots && \vdots
+      \seq_put_right:Nn \l__thermodynamics_matrix_seq
+        { \vdots \c_alignment_token \c_alignment_token \vdots }
+    }
+    {% Ordinary row
+      \clist_map_inline:nn {#4}
+      {
+        \tl_if_in:nnTF {####1} {\dots}
+        {% this column has "dots" in it
+          \seq_put_right:Nn \l__thermodynamics_row_seq \dots
+        }
+        {% Normal column
+          \clist_set_eq:NN \l__thermodynamics_other_vars_clist
+                           \l__thermodynamics_other_vars_copy_clist
+          \clist_remove_all:Nn \l__thermodynamics_other_vars_clist {####1}
+          \bool_if:NTF \l__thermodynamics_found_dots_bool
+          { \tl_set:Nn \l__thermodynamics_Jacobian_temp_tl {\tl_item:nn {####1} {-1}}
+            \seq_put_right:Nx \l__thermodynamics_row_seq
+            {
+              #1\Partial{##1}{####1}
+                  {\allbut{\l__thermodynamics_Jacobian_temp_tl}{\l__thermodynamics_Jacobian_x_tl}}
+            }
+          }
+          { \seq_put_right:Nx \l__thermodynamics_row_seq
+            {
+              #1\Partial{##1}{####1}
+                        {\clist_use:Nn \l__thermodynamics_other_vars_clist ,}
+            }
+          }
+        }
+      }
+      \seq_put_right:Nx \l__thermodynamics_matrix_seq
+      {
+        \seq_use:Nn \l__thermodynamics_row_seq { \c_alignment_token }
+      }
+    }
+  }
+  \tl_if_empty:nTF {#2}
+  {
+    \tl_if_eq:nnTF {#1} {\displaystyle}
+    { \seq_use:Nn \l__thermodynamics_matrix_seq { \\[2.75ex] } }
+    { \seq_use:Nn \l__thermodynamics_matrix_seq { \\[1.25ex] } }
+  }
+  {
+    \seq_use:Nn \l__thermodynamics_matrix_seq { \\[#2] }
+  }
+}
 \endinput
 %%
 %% End of file `thermodynamics.sty'.