[gmx-users] yet another question on pressure fluctuations

[Daniel Cheong]

Dear all,

I am relatively new to Gromacs, having only used it for a month or so.  I
have read through the mailing list and have seen several question regarding
the large fluctuations in pressure observed during the simulations.  This
appears to be normal and expected in small system sizes and microscopic
systems, so I guess there's not too much I can do about that.  But my
question is this: if the pressure exhibits such wild fluctuations, does the
imposed or calculated pressure mean anything?  In other words, say I am
trying to calculate the interfacial tension of an oil-water interface at 1
bar, and I run an NPT simulation, will the calculated surface tension mean
anything when the pressure fluctuations are about 200bars?  Will the imposed
pressure of 1 bar even mean anything at all?  Thanks for any help and
insights you can give.

Daniel