VMD-L Mailing List

From: Christian Jorgensen (chrisjorg_at_gmail.com)
Date: Fri Dec 06 2013 - 11:12:48 CST

Hi there,

I'm wondering if as of Dec. 2013 there is an update regarding the
feasibility of parametrising improper torsions in FFTK?

Thank you in advance

> *Francesco, *
>
> *Currently ffTK does not support the parameterization of improper terms
> (it's on the list). It is of note; however, that there are very few cases
> in which improper terms are required for CGenFF (e.g. carbonyls, planar
> non-cyclic nitrogens). Aromatics generally do not require improper angle
> terms because the torsion potentials are stiff, along with the additional
> constraints of bonded terms within a cyclic context. It's worth taking a
> look through CHARMM and CGenFF parameters to see exactly there improper
> terms are employed and where they are not (I was surprised at how few
> chemical groups require them). *
>