Re: Pressure Discrepancy

From: Morad Alawneh (
Date: Wed Mar 28 2007 - 20:47:16 CDT

*Dear Richard,

I know that I am talking to well knowledgeable persons, and the reason
of using the ideal gas law is again for simplicity, and to allow future
users to understand what we are talking about, specially, if they have
different majors.

Yes, I agree with you that theoretically fixing N, P, and T should make
the fourth parameter to be constant, but practically that is not. The
reason of saying that is coming from the applied methods for keeping P
or T fixed.
Both N or V can be set to an exact value, but P and T are not, and this
can be shown by plotting P or T vs time. But still the average should be
around that fixed value.

After enough time of equilibration the system should be stable and all
the parameters should settle down to their target values.
I think I have so long equilibration, 25 ns, that all these parameters
should have their target values, i.e:
T vs time: is stable ** +/- 10 variation around the **average value that
is close to the target one.
**V vs time: is stable.
**P vs time: is stable, but having too much of **variation around the
**average value that is not close to the target one.*
Right now I am trying Peter's suggestion by making
LangevinPistonDecay 50.0

I will see if that will solve the problem or not.

**I really appreciate the suggestions from all of you.*

Morad Alawneh

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