Also, cd-cc-c3-c3 was introduced only in gaff2 (0.157, 0.0, 3). In gaff,
the force constant of cd-cc-c3-c3 is 0.0 (X-cc-c3-X 6 0.0 3.0).
Best
Junmei
On Tue, Aug 29, 2017 at 9:54 AM, Junmei Wang <junmwang.gmail.com> wrote:
> 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
>>
>> _______________________________________________
>> AMBER mailing list
>> AMBER.ambermd.org
>> http://lists.ambermd.org/mailman/listinfo/amber
>>
>
>
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Received on Tue Aug 29 2017 - 07:30:02 PDT
