Re: [AMBER] Optimal force constant for AMBER

From: David A Case <>
Date: Fri, 12 Aug 2016 10:40:46 -0400

On Fri, Aug 12, 2016, Stregone wrote:
> While I was trying to make a solvent box,
> I realise that there where some parameters missed.
> In my case was the force constant and the angle for a H-C-Br,
> In order to obtain the values, I did import gaff (source leaprc.gaff),
> however those values are not there.

All gaff atom types are lower case; check your dbr.mol2 file to see what
atom types it has. Generally, mol2 files created by antechamber will use
gaff (lower case) atom types; other ways of creating mol2 files may not.

Without knowing more about your mol2 file, and without actually seeing the
error from tleap about missing parameters, it's hard to be of much more help.

> Finally I did compare force constant values,
> H-C-Br 43.18 in the gaff file
> H-C-Br 48.61 the one that I did found.
> What is the real impact of those 5.43 kcal/mol(A)2 difference?

Probably negligable, unless you are trying to calculate detailed vibrational


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Received on Fri Aug 12 2016 - 08:00:02 PDT
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