LaTeX code for some geometrical object in Springer template

Question

I used Springer template svmono for my geometry book. However, some LaTeX code did not display correctly.

In my case, that is the \vec and \neq command.

I want to write the vector so I use \vec for the vector notation. However, it did not display, overrightarrow did display but it is quite ugly. So, what code should I use rather than \vec and overrightarrow?

I also want to use widearc and wideOarc but when I insert the fourier package, it did not display.

What LaTeX code and package is compatible with Springer template svmono?

EDIT As my question still has some new problems, then I posted my MWE here :

\documentclass[graybox,envcountsec,sectrefs,vecarrow,envcountretsec]{svmono}
\usepackage[utf8]{vietnam}
\usepackage{mathptmx}
\usepackage{helvet}
\usepackage{courier}
\usepackage{fourier}
\usepackage{type1cm}           
\begin{document}
$\wideOarc{AB}$: directed arc $\wideOarc{AB}$ 
$\widearc{AB}$: arc.\\
\end{document}

Answer 1

The user guide for svmono says about \vec:

\vec depicts vectors as boldface characters instead of the arrow accent.

and also gives a class option

vecarrow depicts vectors with an arrow above when \vec-command is used.

So

\documentclass{svmono}

\begin{document}

$\vec{a}$

\end{document}

will give

and

\documentclass[vecarrow]{svmono}

\begin{document}

$\vec{a}$

\end{document}

will produce

Regarding the other part of the question, something else must be going on with your settings, since \neq seems to produce the desired result:

\documentclass{svmono}
\begin{document}

$a\neq b$

\end{document}

and just loading fourier gives:

\documentclass[vecarrow]{svmono}
\usepackage{fourier}
\begin{document}

$\vec{a}\quad\widearc{ABC}\quad\wideOarc{ABC}$

\end{document}

A new requirement has been made in an edit to the question: to solve the conflict between fourier and mathptmx, you can simply not load mathptmx or, if you want to load both packages simultaneously (which I think is not really good), you can use the savesym package to change the name of the conflicting symbol, thus preventing the name clash:

\documentclass[graybox,envcountsec,sectrefs,vecarrow,envcountretsec]{svmono}
\usepackage[utf8]{vietnam}
\usepackage{savesym}
\usepackage{mathptmx}
\savesymbol{hbar}
\usepackage{helvet}
\usepackage{courier}
\usepackage{type1cm}           
\usepackage{fourier}
\begin{document}
$\wideOarc{AB}$: directed arc $\wideOarc{AB}$ 
$\widearc{AB}$: arc.
\end{document}