How to create the character Д for math mode? [duplicate]

Question

In my research I'm using results of the paper Vinogradov A. M., - The logic algebra for the theory of linear differential operators, - Soviet Math. Dokl., 13 (1972), 1058-1062. The paper uses the character looking like Д (Unicode hex U+0414) to refer to a specific operator:

What I want is to write something like \newcommand\DD{\unicodesymbol{U+0414}} (which obviously doesn't work) and use \DD to refer to this symbol in math mode. I've also found, that

\usepackage[OT2, T1]{fontenc}
\usepackage[russian, english]{babel}
\newcommand\DD{ {\operatorname{\textrm{\foreignlanguage{russian}{D}}}} }

seems to work, but I'm not sure, if this is a good way to define this symbol (e.g. if it doesn't break anything).

So, what is the best way to do that?

P.S. I tried to use Detexify, as suggested here, and didn't find anything like Д. I also looked at Comprehensive LaTeX symbols and AMS LaTeX Short Math Guide, and the most close equivalend I've found is \symrook from skak package, which is still different.

Update: as was suggested in a comment below by Gonzalo Medina I now use

\usepackage{amsmath}
\usepackage[OT2, T1]{fontenc}
\usepackage[russian, english]{babel}
\DeclareMathOperator\DD{\textrm{\foreignlanguage{russian}{D}}}

Answer 1

This variant of \DD

• uses the cm-super fonts for the Cyrillic glyph (the fonts are available s Type 1 fonts and avoid bitmap fonts),
• supports \boldsymbol or \mathversion{bold},
• is resizable,
• does not need package babel,
• only requires a font encoding that provides \CYRD (e.g. T2A).

Example file:

\documentclass{article}
\usepackage{amsmath}
\usepackage[T2A,T1]{fontenc}
\makeatletter
\newcommand*{\math@version@bold}{bold}
\DeclareMathOperator\DD{% or \DeclareMathOperator*\DD
  \textrm{%
    \usefont{T2A}{cmr}{\ifx\math@version\math@version@bold bx\else m\fi}{n}%
    \CYRD
  }%
}
\makeatother
\begin{document}
\[\DD^{\DD^{\DD}} = \boldsymbol{\DD^{\DD^{\DD}}}\]
\end{document}