AMBER Archive (2008)

Subject: Re: AMBER: Constant pH with new parameters (amber10)

From: David A. Case (
Date: Fri Jul 11 2008 - 13:41:09 CDT

On Tue, Jul 08, 2008, Markus Kaukonen wrote:
> Is it ok to set up a constant pH calculation with leap commands in Amber 10:
> >source leaprc.ff03
> >set default PBRadii mbondi2
> >loadoff constph.lib
> >loadamberparams frcmod.constph
> I mean, are the force fied modifications in the manual only valid when using
> 'source leaprc.ff99' or can one use 'source leaprc.ff03'

I believe that constph.lib files are based on the ff99 charges, and so would
not be fully compatible with ff03.

> Is the file 'frcmod.mod_phipsi.1' needed anymore for constant pH?

You want to use leaprc.ff99SB. Then you don't need the mod_phipsi stuff, as
it is automatically included.

...good luck...dac

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