Re: [AMBER] Negative Pressure During Equilibrium

From: Jason Swails <>
Date: Tue, 9 Jul 2013 08:20:47 -0400

On Mon, Jul 8, 2013 at 8:25 PM, Parker de Waal <>wrote:

> Hi AMBER Users!
> I just finished a 1 ns equilibrium run and all of my parameters seem to
> have leveled out fine except for pressure which averaged at -0.2514

Yes, this seems reasonable. Note that since liquids are nearly
incompressible, small changes in volume yield much larger fluctuations in
pressure. If you look at the pressure, the fluctuations should be
significantly larger than 1 (units are 'bar' here).

The more instructive property to look at when you are doing constant
pressure simulations is the density.


Jason M. Swails
Quantum Theory Project,
University of Florida
Ph.D. Candidate
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Received on Tue Jul 09 2013 - 05:30:04 PDT
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