[gmx-users] parrinello-rahman to wrong pressure
michel.cuendet at epfl.ch
Thu Oct 16 14:14:00 CEST 2003
Hi gmx fans,
After heating up my system with a slightly oversized fixed box, I
start the equilibration with a barostat (parameters below). How is it
possible that parrinello-rahman expands the box and maintains an average
pressure of about -1900 bar (over 100's of picoseconds) ? All conditions
identical, the berendsen barostat decreases the box size and then keeps
a reasonable pressure. It seems that the final pressure for
parrinello-rahman depends on the size of the system : with more water,
it reaches a pressure of -2400 bar.
Has anyone an explaination ?
tcoupl = nose-hoover
tc-grps = Protein
tau_t = 0.1
ref_t = 300.0
Pcoupl = berendsen / parrinello-rahman
tau_p = 1.0
compressibility = 4.5e-5
ref_p = 1.0
PS: My previous message about thermostats in presence of a frozen
group has still not been replied.
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