[gmx-users] berendsen vs parrinello-rahman

[Nilesh Dhumal]

Hello,

I am running the simulation for ionic liquids. I initially did simulation
with Gromacs VERSION 4.0.7  with "parrinello-rahman" pressure coupling.
Here I pasted temperature and pressure coupling part of mdp file.

; Temperature coupling is on
Tcoupl = v-rescale
tau_t = 0.1
tc-grps  =system
ref_t =   350
; Pressure coupling is  on
Pcoupl              = parrinello-rahman
pcoupltype          = isotropic
tau_p               =  0.5
compressibility     =  4.5e-5
ref_p               =  1.0

We updated gromacs version to recent  Gromacs VERSION 4.5.5.  With these
parameter during equilibration, I got the error "system is blowing up".  I
changed "parrinello-rahman" pressure coupling to berendsen and able to run
the simulation.

; Temperature coupling is on
;Tcoupl =  Nose-Hoover
tau_t = 1.0
tc-grps  =system
ref_t = 400.0
; Pressure coupling is  on
Pcoupl              = berendsen;  parrinello-rahman
pcoupltype          = isotropic
tau_p               =  0.5
compressibility     =  4.5e-5
ref_p               =  1.0

Is there any changes in recent version in pressure coupling?

Thanks

Nilesh