[gmx-users] Pressure estimation from NVT

[Dallas Warren]

Have you looked at the data from which you calculated the pressure average from?

Catch ya,

Dr. Dallas Warren
Medicinal Chemistry and Drug Action
Monash Institute of Pharmaceutical Sciences, Monash University
381 Royal Parade, Parkville VIC 3010
dallas.warren at monash.edu
+61 3 9903 9304
---------------------------------
When the only tool you own is a hammer, every problem begins to resemble a nail.

From: gmx-users-bounces at gromacs.org [mailto:gmx-users-bounces at gromacs.org] On Behalf Of Sikandar Mashayak
Sent: Tuesday, 27 September 2011 3:48 AM
To: Discussion list for GROMACS users
Subject: [gmx-users] Pressure estimation from NVT

Hi

I am trying to determine pressure of water at given density and temperature using SPC/E water model. To achieve this, I am doing NVT bulk simulations and then using g_energy I get average pressure values. The question I have is how accurate these average pressure predictions are?

e.g. I get average pressure of 185 bar for 300 K and 1 g/cm^3 water density, but theoretical value for it is around 1 bar. What are the possible reasons for this much deviation from theoretical value? Is there anything wrong with my set up? I am using 2141 water molecules in 4*4*4 periodic box, Nose-Hoover thermostat with 0.2ps time constant , MD algorithm with 1fs time-step, LJ with 1.5 nm cut off and PME for electrostatics.

thanks
sikandar
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