When using GAFF on Windows (64 bit, Windows 7), it gives incorrect results such as bonds are too short and bond angles are compressed. I’ve tested this in Avogadro 1.1.0 and 1.1.1 and both versions produce the same result. However, 1.1.0 on Ubuntu works correctly. Additionally, all the other force fields work correctly. Perhaps there is a sign error or unit conversion wrong in the Window’s version?