Switching from two columns to one column without adding a page break

Question

I am trying to adapt this solution, shown below, of multiple authors and multiple affiliations:

                   

to a format where, title and authors go in single column at the top of the first page, but the regular text flows in two columns. See a snapshot of the original template at the bottom of this post.

I tried inserting \onecolumn prior to the author and title affiliations, and then immediately switching back to \twocolumn, but LaTeX creates a full page break before the regular text (abstract etc) is rendered. How can I avoid this page break?

\documentclass{article}
\usepackage{spconf,amsmath,graphicx}
\usepackage{url}
\usepackage{amssymb}
\usepackage{caption}
\usepackage[labelformat=simple]{subcaption}
\usepackage{calc}
\usepackage{enumitem}
\usepackage{kantlipsum}
\usepackage{array}

\newcommand\Mark[1]{\textsuperscript#1}

\begin{document}
\onecolumn
\begingroup
\centering
{\LARGE The Title \\[1.5em]
\large First Author\Mark{1}, Second Author\Mark{2}, Third Author\Mark{1}, Fourth Author\Mark{2} and Fifth Author\Mark{3}}\\[1em]
\begin{tabular}{*{2}{>{\centering}p{.25\textwidth}}}
\Mark{1}Department1 & \Mark{2}Department2 \tabularnewline
School1 & School2  \tabularnewline
\url{email1} & \url{email2}
\end{tabular}\par
\twocolumn
\endgroup

\begin{abstract}
This text should be back in two columns
\end{abstract}

\end{document}

Answer 1

Put the title material in the optional argument to \twocolumn. In the example I use only the specific packages needed.

The only point to remark is the additional pair of braces because you have [] in the code.

\documentclass[twocolumn]{article}
\usepackage{array,url,kantlipsum}

% \Mark is probably provided by spconf, that I don't have
\newcommand{\Mark}[1]{\textsuperscript{#1}}

\begin{document}
\twocolumn[{%
 \centering
 \LARGE The Title \\[1.5em]
 \large First Author\Mark{1},
        Second Author\Mark{2},
        Third Author\Mark{1},
        Fourth Author\Mark{2}
    and Fifth Author\Mark{3}\\[1em]
 \normalsize
 \begin{tabular}{*{2}{>{\centering}p{.25\textwidth}}}
  \Mark{1}Department1 & \Mark{2}Department2 \tabularnewline
  School1 & School2  \tabularnewline
  \url{email1} & \url{email2}
 \end{tabular}\\[3em] % some more space after the title part
}]

\begin{abstract}
This text should be back in two columns
\end{abstract}

\section{Introduction}
\kant

\end{document}