[gmx-users] compression- NPT

Mark Abraham Mark.Abraham at anu.edu.au
Thu Apr 14 02:14:10 CEST 2011

On 14/04/2011 4:36 AM, Moeed wrote:
> Hello everyone,
> I have encountered a strange behavior while compressing a pure system.
> I am applying 100 bar pressure with PME and it turned out that this 
> pressure leads to density of 20 SI. Changing PME to SHIFT compresses 
> the system to density of above 600 SI!! and I should add that PME and 
> shift on my system give essentially identical results ( I mean all 
> those properties listed in g_energy)

Why are you changing units of pressure mid-sentence?

> Also, when I take a configuration from a run which is compressed to a 
> higher density which is still off the desired density, applying a even 
> higher pressure in the next run not only does not leads to further 
> compression but causes the box expand to a much bigger size!

All this sounds so wildly unlikely that you must be mismatching files, 
or similar. Start from a fresh working directory and see what you can 
reproduce. Extraordinary claims require extraordinary evidence.


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