main.tex

\documentclass[preprint]{elsarticle}

\usepackage{amsmath,amsthm,amssymb}
\usepackage{graphicx}% Include figure files
\graphicspath{{submission/figs}}

\usepackage{dcolumn}% Align table columns on decimal point
\usepackage{bm}% bold math
\usepackage{color}
\usepackage{epsfig}
\usepackage{multirow}
\usepackage{mathrsfs}
\usepackage{hyperref}
\usepackage{cleveref}
\usepackage{epstopdf}
\usepackage{subfigure}
\usepackage{autobreak}



%Macros for mathematical notations

\newcommand{\V}[1]{\boldsymbol{#1}} %# vector
\newcommand{\M}[1]{\boldsymbol{#1}} %# matrix
\newcommand{\Set}[1]{\mathbb{#1}} %# set
\newcommand{\D}[1]{\Delta#1} %# \D{t} for time step size
\renewcommand{\d}[1]{\delta#1} %# \d{t} for small increment
\newcommand{\norm}[1]{\left\Vert #1\right\Vert } % norm
\newcommand{\abs}[1]{\left|#1\right|} %abs

\newcommand{\grad}{\M{\nabla}} %gradient
\newcommand{\av}[1]{\left\langle #1\right\rangle } %take average

\newcommand{\sM}[1]{\M{\mathcal{#1}}} %matrix in mathcal font
\newcommand{\dprime}{\prime\prime} % double prime
%\global\long\def\i{\iota}
%\renewcommand{\i}{\iota} %i for imaginary unit
%\renewcommand{\i}{\mathsf i} %i for imaginary unit
\newcommand{\follows}{\quad\Rightarrow\quad} %=>
\newcommand{\eqd}{\overset{d}{=}} %=^d
\newcommand{\spe}[1]{\mathscr{#1}}  %important quantities in mathscr font
\newcommand{\eps}{\epsilon}
\usepackage{color}
\newcommand{\rev}[1] {{\color{blue}#1}}
\newcommand{\gao}[1] {{\color{red}{\textit{xz comment}}: \color{red}#1}}

\begin{document}
\preprint{Preprint}

\title{Atricle Title}

\date{\today}

%%%%% Begin Abstract %%%%%%%%%%%
\begin{abstract}

\end{abstract}

%%%%% end %%%%%%%%%%%

\begin{keyword}
    
\end{keyword}
%%%% maketitle %%%%%
\maketitle

%%%% Start %%%%%%


\bibliography{groupbib}



\end{document}