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 return 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’.