Dear Ghemical-Devel, Looking ahead, the GAMESS group at UIowa/AmesLab is looking at implementing some GAMESS specific functionality (which of course will be implemented as optional) but the operation includes creating a new structure to hold this information, along with requiring the code to find molecules that are the same. For example, selecting one molecule and finding all similar molecules (finding all water molecules). I was just wondering what facilities are already included in the ghemical code that would help do this, or any algorithms that would help. One idea was to convert the molecules using openbabel to the SMILE format and then doing a string comparison. Any suggestions would be helpful. -Donald