Symbols above the letters (for scientific publications)

When writing papers, we often come up with author(s) names with symbols above some characters of author(s) names.

How do you use those symbols in LaTeX?

Here is a Wikipedia link where the details are provided.

https://en.wikipedia.org/wiki/Diacritic

In order to use in LaTeX, a number of answers in the following SE site is given.

https://tex.stackexchange.com/tags/accents/info

Some of the frequently used symbols are (from SE site):

Text mode

Plain TeX makes it possible to typeset the most commonly used accents:

• \` (grave accent): à
• \' (acute accent): á
• \^ (circumflex or “hat”): â
• \" (umlaut or dieresis): ä
• \~ (tilde or “squiggle”): ã
• \= (macron or “bar”): ā
• \. (dot accent): ȧ
• \u (breve accent): ă
• \v (háček or “check”): ǎ
• \H (long Hungarian umlaut): ő
• \t (tie-after accent): a͡
• \c (cedilla): ş
• \d (dot-under accent): ạ
• \b (bar-under accent): ο̩
• \k (ogonek): ą

The Unicode character encoding UTF8 includes several special characters and characters with accents. The following code specifies that the encoding of the LaTeX document source file is UTF8. As font encoding is specified T1, because it supports the encoding of extended character sets in fonts:

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

Of course, the encoding in the text editor needs to be set to utf8, as well.

Math mode

The following commands may be used only in math mode to produce accents;

• \hat{o} (circumflex): 
• \widehat{oo} (wide version of \hat over several letters): 
• \check{o} (vee or check): 
• \tilde{o} (tilde) 
• \widetilde{oo} (wide tilde) 
• \acute{o} (acute accent): 
• \grave{o} (grave accent): 
• \dot{o} (dot over the letter): 
• \ddot{o} (two dots over the letter): 
• \breve{o} (breve): 
• \bar{o} (macron): 
• \vec{o} (vector (arrow) over the letter):