Hello, Johannes,
When you ran parmchk2, did you specify to use gaff2 with "-s 2"? The
default FF to use is gaff, not gaff2.
I constructed two triazole molecules (ethyl triazole and
5-ethyl-1H-1,2,3-triazole) and assigned both gaff and gaff2 atom types. I
didn't find a problem with the four frcmod files produced by parmchk2.
Please also use "-at gaff2" when you run antechamber to assign gaff2 atom
types.
Please let me know if you have more questions.
Best
Junmei
On Tue, Aug 22, 2017 at 4:47 AM, Traeg, Johannes <johannes.traeg.fau.de>
wrote:
> Hi AMBER users,
>
> I'm having trouble with a GAFF2 force field that I generated with
> ANTECHAMBER/LEAP. My molecule contains a triazole unit with an ethyl
> group connected to one of the carbon atoms of triazole. ANTECHAMBER
> correctly recognizes the atom types and, hence, my molecule contains the
> dihedral CC-CD-C3-C3 (CC and CD are identical in GAFF/GAFF2). The
> .prmtop file lists the following parameters for this dihedral:
>
> force constant = 0.0
> phase = 0.0
> periodicity = 3
>
> However, the GAFF2.dat file (Amber16) lists the following parameters for
> the dihedral CD-CC-C3-C3, which should be identical to CC-CD-C3-C3 (due
> to the equivalence of CC and CD):
>
> force constant = 0.157
> phase = 180.0
> periodicity = 3
>
> Can anyone help me out with this problem?
>
> Thanks in advance and best regards,
>
> Johannes
>
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Received on Tue Aug 29 2017 - 07:00:02 PDT
