[gmx-users] pressure coupling

[kordzadeh at aut.ac.ir]

Hi all

I want to investigate carbin nanotube as drug carrier I want to fnctionalize CNT and compare results with experimental but I have a problem

functionalization performed in constant pressure 1 atm . Pressure in my system converges hard and I try several times I changed time step , number of steps and time constant but I didn't obtan a specific trend for pressure coupling. after 40 runs my best results is:

Energy                      Average   Err.Est.       RMSD  Tot-Drift
-------------------------------------------------------------------------------
Pressure                    1.49409       0.63    295.065    2.01005  (bar)

 

an example mdp file for npt is:
 

; Pressure coupling is on

pcoupl         = Parrinello-Rahman     ; Pressure coupling on in NPT

pcoupltype         = isotropic             ; uniform scaling of box vectors

tau_p         =  2             ; time constant, in ps

ref_p         =  1.0             ; reference pressure, in bar

compressibility     = 4.5e-5              ; isothermal compressibility of water, bar^-1

what should I do? 

any suggest will be appreciated

Thanks

Azadeh

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