findHM: Correct spelling for Herman-Mauguin space groups symbols
Description
The commonly-used spelling of a crystallographic space group does not match the correct definition
given by the Herman-Mauguin symbols which define all space groups in a unique and precise way. This
function attempt to translate a tentative string into a possible Herman-Mauguin symbol, if it finds
one. If the input string is already in the extended Herman-Mauguin form, the same string is returned
as output.
Usage
findHM(sym_xHM)
Value
SG A character string. The extended Hermann-Mauguin symbol (e.g. 'P 1 1 21').
Arguments
sym_xHM
A character string. The space group symbol in its commonly-used spelling.