[gmx-users] RE: average pressure of a system

Dwey Kauffman mpi566 at gmail.com
Wed Sep 11 06:12:37 CEST 2013


>True, but thermostats allow temperatures to oscillate on the order of a few
K, 
>and that doesn't happen on the macroscopic level either.  Hence the small 
>disconnect between a system that has thousands of atoms and one that has 
>millions or trillions.  Pressure fluctuations decrease on the order of
sqrt(N), 
>so the system size itself is a determining factor for the pressure
fluctuations. 
>  As previous discussions have rightly concluded, pressure is a somewhat 
>ill-defined quantity in molecular systems like these.

Dose it also imply that it is not a good idea to study the relationship
between dimer (multimer) dissociation and  macroscopic pressure in this case
?  (due to the ill defined pressure).

It is hard to be justified if I assign a set of various ref_p= 0.7, 0.8,
0.9, 1.0, 1.1, 1.2 ...., perform independent simulations, and then obtain
outcomes of targeted quantities for comparison.  

>
>You could try altering tau_p, but I doubt there is any value in doing so.

I would give it a try.

Thanks for the hint.

Dwey


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