A simple tex file to test the fontawesome5 package as a replacement for ifsym

main.tex

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%%% LaPreprint: PREPRINT TEMPLATE
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\documentclass[9pt,arxiv]{lapreprint}

% Import packages
\usepackage[version=4]{mhchem} % For chemical notation
\usepackage{siunitx}    % For SI units
\usepackage{pdflscape}  % For putting pages in landscape mode
\usepackage{rotating}   % For rotating specific elements
\usepackage{textgreek}  % Greek symbols
\usepackage{gensymb}    % Symbols
\usepackage{fontawesome5} % For the \faEnvelope symbol
\faStyle{regular}         % Default fontawesome icons style to outline
\usepackage{orcidlink}  % For the \orcidlink
\usepackage{listings}   % For inserting code chunks
\usepackage{colortbl}   % For Knitr table colouring
\usepackage{tabularx}   % For making Knitr tables compatible
\usepackage{longtable}  % For multi-page tables
\usepackage{subcaption}
\usepackage{multirow}
\usepackage{snotez}     % For sidenote environments. enotez for endnotes
\usepackage{csquotes}   % For language-based quote rules (helps BiBLaTeX)
\usepackage{url}
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% Make declarations
\DeclareSIUnit\Molar{M}

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%%% BIBLIOGRAPHY
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\usepackage{hyperref}
\usepackage[			% use biblatex for bibliography
	backend=biber,      % use biber or bibtex backend
    style=authoryear,   % choose style
	natbib=true,		% allow natbib commands
	hyperref=true,	    % activate hyperref support
	alldates=year,      % only show year (not month)
]{biblatex}

% Just avoiding some rogue fields that cause issues with certain styles
\AtEveryBibitem{
    \clearfield{urlyear}
    \clearfield{urlmonth}
    \clearlist{language}
}

% Update to your bibliography file
\addbibresource{main.bib}

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%%% ARTICLE SETUP
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% Paper title
\title{A modest idea}

% Authors - you can use \orcidlink{} and \authfn{} - see contribution note
\author[ \orcidlink{0000-1234-5678-9012} 1, 2 \faEnvelope]{Jane Doe}

% Affiliations
\affil[1]{Earth}
\affil[2]{The Moon}

% Other metadata. Feel free to add your own
\metadata[]{\faEnvelope\hspace{.5ex} For correspondence}{jdoe@earth.com}
\metadata[]{Keywords}{markdown; open-science}


% Surname of the lead author(s) for the running footer
\leadauthor{Jane Doe}
\shorttitle{Modestly}

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%%% ARTICLE START
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\begin{document}
\maketitle

\begin{abstract}
We introduce a simple idea.
\end{abstract}

\subsection*{Background}

Why is this important? 

\begin{enumerate}
\item Not sure
\item Will figure it out later
\end{enumerate}

Some math might help us here?

\begin{equation}
x+\gamma + \alpha
\end{equation}

\end{document}