Re: Configuration file

From: Jeffrey J. Potoff (
Date: Tue Mar 06 2007 - 08:22:18 CST

Rita Cassia wrote:

>Dear All,
>after creating an ethanol box, I had done simulations from 0K to 150K (2 ps), then another one, heating until 300K (NVT) for 60 ps. But I'm facing problems when I want to make a simulation (NPT) to equilibrate the density. The simulation stops , with the message
>"Periodic cell has become too small for original patch grid; Possible solutions are to restart from a recent checkpoint,
>increase margin, or disable useFlexibleCell for liquid simulation."
>I would appreciate if someone can give me some tips.
Hi Rita,
    What is likely happening is your simulation box is blowing up as
soon as you start the NPT simulation. You can verify this by printing
every timestep once you start the NPT simulations. Are you using the
Charmm force field, or are you using something different, like OPLS?


Jeffrey J. Potoff
Assistant Professor			  Wayne State University		
Department of Chemical Engineering and Materials Science
5050 Anthony Wayne Dr			  Phone:(313)577-9357		
Detroit, MI 48202  	                  Fax:  (313)577-3810

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