AMBER Archive (2006)

Subject: Re: AMBER: How to specify user defined force fields or its parameters in amber??

From: Gustavo Seabra (gustavo.seabra_at_gmail.com)
Date: Thu Nov 30 2006 - 09:46:42 CST


Hi Gobind,

Sorry for the delay. Notice that the suggestion I sent you before will
zero ALL bond constants of a specific TYPE, not a specific bond. In
your case, it seems that yoou need some extra control, so it might
actually not be such a good idea.

One thing I imagine you could do is to go back to Leap and try to
tweak the force constants there. I imagine you would have to re-define
the atoms you are interested so that the interaction involving those
atoms are unique, and then you can zero the constants only to those
interactions. (But I think other people in this list are more
qualified to give you more details on how.)

Good luck!

Gustavo

On 11/28/06, Gobind Singh Bisht <gsbisht1_at_gmail.com> wrote:
> hi,
> well actuallly what i want to do is drop all the terms except for lennard
> jones for some of the atoms in the system. is thr a similar short cut way of
> achieving that??
> thanx a lot
> cheers
>
>
> On 11/28/06, Gustavo Seabra <gustavo.seabra_at_gmail.com> wrote:
> > On 11/28/06, Gobind Singh Bisht <gsbisht1_at_gmail.com> wrote:
> > > isn't it possible that u make Kr=0 for all the bonds or few bonds in my
> system.
> > ^^^^^^^
> >
> > For that, all yoou need is to look for the section in the parmtop file
> with the header:
> >
> > %FLAG BOND_FORCE_CONSTANT
> >
> > and then set the values you want to zero, no programming needed. (Make
> sure you don't change the formatting)
> >
> > Gustavo.
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