[gmx-users] why the pressure fluctuated wildly during the simulation?

[Justin A. Lemkul]

杜波 wrote:
> when i simulate in the NPT , and the parameter are set as follow,
> 
> Pcoupl                   = Parrinello-Rahman
> pcoupltype               = isotropic
> ; Time constant (ps), compressibility (1/bar) and reference P (bar)
> tau_p                    = 5
> compressibility          = 6.5e-5
> ref_p                    = 1.0
> 
> and the result:
> Energy                      Average   Err.Est.       RMSD  Tot-Drift
> -------------------------------------------------------------------------------
> Total Energy                30582.9        8.1    301.475      34.36  (kJ/mol)
> Temperature                     500    2.9e-05    10.6006 -3.11052e-05  (K)
> Pressure                    1.68994      0.044    1199.11 -0.0909901  (bar)
> 
> we can see the RMSD  of Pressure is so big !!!
> why the pressure fluctuated wildly during the simulation?

Sounds normal.

http://www.gromacs.org/Documentation/Terminology/Pressure

-Justin

-- 
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Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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