[gmx-users] Pressure at constant volume

[Erik Marklund]

17 maj 2012 kl. 05.00 skrev Juliette N.:

> Hello everyone,
> 
> I am trying to estimate the thermodynamic expression, dP/dw at
> constant V and T, for my polymer-solvent system. Where P is the
> pressure, w is the mass fraction, V volume and T temperature. I guess
> this task can not be done by MD, as for constant Volume, pressure is
> meaningless. Since what g_energy reports is not the actual pressure
> which corresponds to that fixed Volume. Am I correct?

Hi, I lost you there. Why is pressure meaningless at constant volume?

Best,

Erik

> 
> (I mean building different binary systems with different mass
> fractions of w, and measuring average P (dP/dw) while keeping T and V
> constant does not produce meaningful results by MD)
> 
> Please comment if this makes sense in MD or not.
> 
> Thanks,
> J.
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-----------------------------------------------
Erik Marklund, PhD
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,    75124 Uppsala, Sweden
phone:    +46 18 471 6688        fax: +46 18 511 755
erikm at xray.bmc.uu.se
http://www2.icm.uu.se/molbio/elflab/index.html

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