Chemical standard state symbol with achemso article

Question

I am completely new to LaTeX, but I know how to use the chemstyles package to generate the standard state plimsoll in a document that I am working on for, say, my students, etc. However, for generating an ACS article, the standard state symbol does not seem to work when I use the achemso package.

Example code:

\documentclass[journal=jacsat,manuscript=article]{achemso}
\usepackage[version=4]{mhchem}
\usepackage{chemstyle}

\title{A title}

\begin{document}

$$\Delta_\mathrm{rxn} G^\standardstate$$

\end{document}

Changing the documentclass to article fixes the issue. Is there a way to generate the standard state symbol simply with the achemso package?

Answer 1

It looks like a clash between achemso and chemstyle packages. Since ACS guidelines only strongly encourage to use achemso, the functionality of chemstyle (which also hasn't been updated since 2013) can be replicated by other means. Since ACS suggests to

Avoid extensive use of \newcommand and \def

I'm not listing any methods of creating own symbol (see e.g. How to draw a Plimsoll? on latex.org).

Method 1. Use \standardstate from chemmacros's symbols module

\documentclass[journal=jacsat,manuscript=article]{achemso}
\usepackage{chemmacros}
    \chemsetup{modules={all}}

\title{A title}

\begin{document}

\[\Delta_\mathrm{rxn}G^\standardstate\]

\end{document}

Method 2. Use \minuso from stmaryrd package

\documentclass[journal=jacsat,manuscript=article]{achemso}
\usepackage{amsmath}
\usepackage{stmaryrd}

\title{A title}

\begin{document}

\[\Delta_\mathrm{rxn}G^\minuso\]

\end{document}

Method 3. Use \stst from plimsoll package

Note: aside from \stst macro which is probably the optimal choice for chemists and is a recommended way of typesetting standard state symbol listed in The Comprehensive LaTeX Symbol List (accessed 2021-05-22), package plimsoll offers options for sans serif version of “⦵” symbol (sans) and redefinition of \circ macro to display plimsoll symbol (circ). If the symbol is used for a purpose different from denoting standard state, there is a more semantically correct \plimsoll macro (for use in math mode).

\documentclass[journal=jacsat,manuscript=article]{achemso}
\usepackage{plimsoll}

\title{A title}

\begin{document}

\[\Delta_\mathrm{rxn}G\stst\]
    
\end{document}

Kudos to Linear Christmas for the suggestion to include the package to this list!

Method 4. Use xelatex and a Unicode font with a support for ⦵ glyph

Note: probably the least portable method and not recommended for ACS submissions. Requires to bundle extra font or make absolutely sure the font is installed on a target system, and uses a compiler different from pdflatex.

% !TEX program = xelatex

\documentclass[journal=jacsat,manuscript=article]{achemso}
\usepackage{fontspec}
    \setmainfont{STIX Two Text}
\usepackage{unicode-math}
    \setmathfont{STIX Two Math}

\title{A title}

\begin{document}

\[Δ_\mathrm{rxn}G^⦵\]

\end{document}

Answer 2

If you don't want to install a package just for the standard-state symbol, you can create a mock-up:

\newcommand\standardstate{{\circ\kern-0.495em-}}

$ \Delta G = \Delta G^{\standardstate} + RT\ln(Q) $

A disadvantage is that the \kern-0.495em may need a bit of tweaking depending on the font. This works computer modern 11pt. In computer modern 12pt, use -0.47em; in 10pt, use -0.525em.

Use this for reports that you will distribute as PDF. Journals probably won't like this in submissions.