[gmx-users] Pressure and box volume

Justin Lemkul jalemkul at vt.edu
Mon Mar 20 12:54:38 CET 2017

On 3/19/17 8:42 PM, Mishelle Oña wrote:
> Hello Justin!
> I was trying to getting down the pressure of my simulation from aprox 300 bar to 1 bar. I increased the box volume and now I have 27 bars but my density decrease dramatically from 970 to 320 kg/m3. I tried to add more water molecules to increase it again but then the pressure scaled up to 300 bar again. To make a production simulation we should equilibrate the parameters of Temperature, Pressure, density and Volume. Should I continue playing with the size of the box and the amount of water molecules until I get all this parameters acording to the conditions I want or is anything else I can do instead?

"Randomly toying with box size and water content" is not a reproducible method :)

We're missing a lot of context here, like everything you've done up to this 
point, so it's really hard to comment.  But in general, it is certainly not 
necessary to make all these ad hoc changes.  You may just have to wait a while 
for the pressure to stabilize, depending on how far from equilibrium your 
initial state was (and it sounds like it was pretty far from your desired value).



Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441


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