MMFF94 gives weird results

User f52820d97e

14-11-2013 13:56:04


I am trying to figure out the behavior of the minimization forcefields. The MMFF94 results gives very strange results.

Here is the molecule I tried:


in the online version, the cycles are bent which is impossible

in my desktop version (5.12.3) the cycles are OK but the aromatic nitrogen has a wrong geometry - it seems that it is treated as sp3 and not sp2

the dreiding geometry seems correct, though.

any explanation/advice?



ChemAxon 5fc3e8d7d0

20-11-2013 16:02:35

Dear Nicolas,

Thanks for the report. We could reproduce the issue.
It seems there is a bug in MMFF94 atomtypizer (if N-atom is in an aromatic ring).

We will send you a notification, if the bug is fixed.

Best regards,