Correct spelling for Herman-Mauguin space groups symbols

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)

Arguments

sym_xHM

A character string. The space group symbol in its commonly-used spelling.

Value

SG A character string. The extended Hermann-Mauguin symbol (e.g. 'P 1 1 21').

Examples

# P21
print(find("P 21"))
#> character(0)

# P -1
print(find("P-1"))
#> character(0)