AMBER Archive (2003)

Subject: Re: vlimit exceeded when sander calculate free energies using TI

From: David A. Case (case_at_scripps.edu)
Date: Wed Jun 11 2003 - 10:21:31 CDT

On Wed, Jun 11, 2003, zsx wrote:

> I have used the Cap water , ibelly=1 and ntb=0, it can run normally
> dynamics in sander7, but when I use the normal dynamic *.rst as the input
> file for sander7 TI calculation, icfe=1 and clambda=0.04691, the VDW energy
> and Temperature will increase uncontrolly, then break down. I want to know
> the reason, for it seem that it will go normally with period condition
> system.

There is probably some problem with your prmtop setup. The first thing you
should always do with problems like this is run a 10-20 step simulation
with ntpr=1. That way, you can see the energies and their differences in
detail. If the reported DV/DL number is big, there is something wrong with
the perturbed prmtop file. Try running short simulations at both lambda=0
and lambda=1, and see if you can identify what the problems are.

..good luck...dac 

-- 

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David A. Case                     |  e-mail:      case_at_scripps.edu
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