unsigned int OEGetAtomicNum(const char *sym)
Returns the atomic number associated with the specified atomic symbol.
The specified buffer
sym must contain a string terminated by either
a space or a NULL,
\0, character. Zero-length strings, strings
longer than two characters or unrecognized symbols all make the function
0. The comparison is case insensitive, such that the first
character need not be uppercase, and the second character (if one
exists) need not be lowercase.
This function returns the value
1 for symbols ‘H’, ‘D’ and ‘T’.