MMFF94 gives weird results

Hi,

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:

[H]N(C(=S)c1nc([H])c([H])c2c(c3n(c4c([H])c([H])c(OC(=S)C([H])([H])[H])c([H])c4c3c([H])c12)C([H])([H])[H])C([H])([H])[H])C([H])([H])C([H])([H])[N+]([H])(C([H])([H])[H])C([H])([H])[H]

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?

thanks

Nicolas

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,
Laszlo