[gmx-users] Pressure Fluctuations

[Kavyashree M]

Dear users,

Upon was trying to simulate an npt ensemble (protein in water),
pressure was coupled using  parinello rahman system with tau_p = 2,
tau_t = 1; compressibility 4.5e-5, type = isotropic.

(cut off scheme (vdw_type = switch; rvdw = 1.0; rvdw_switch = 0.9;
rcoulomb = 1.2; rlist = 1.2).

No matter what value of tau_p is used (0.5, 1, 2, 2.5, 3, 3.5), the pressure
fluctuations are very drastic. I have gone through the mailing list
regarding
this issue but could not come to any conclusion.

Any suggestions are helpfull.

This is one of the statistics for pressure fluctuations.

Statistics over 500001 steps [ 0.0000 through 1000.0000 ps ], 1 data sets
All statistics are over 100001 points

Energy                      Average   Err.Est.       RMSD  Tot-Drift
-------------------------------------------------------------------------------
Pressure                    5.77629       0.99    398.013   -5.34218  (bar)


Thanking you
With Regards
M. Kavyashree
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20110316/720e4259/attachment.html>