[gmx-users] wierd pressure!

[Rongliang Wu]

Hello gmx-users,

	i simulated a 4 4 10 box of benzene with pressure coupling, the first 1000ps goes well, but after 1000ps the pressure decreases linearly to -300 bar and the desity goes beyond 1000g/l.

my mdp file is as follows:
title                    = god!
cpp                      = /usr/bin/cpp
include                  = 
define                   = 
integrator               = md
dt                       = 0.002
nsteps                   = 500000
nstxout                  = 20000
nstvout                  = 20000
nstlog                   = 20000
nstenergy                = 50
nstxtcout                = 20000
xtc_grps                 =
energygrps               =
nstlist                  = 10
ns_type                  = grid
rlist                    = 1.0
coulombtype              = cut-off
rcoulomb                 = 1.4
rvdw                     = 1.4
tcoupl                   = Berendsen
tc-grps                  = system
tau_t                    = 0.05
ref_t                    = 300
Pcoupl                   = Berendsen
Pcoupltype               = semiisotropic
tau_p                    = 0.1
compressibility          = 0 4.5e-5
ref_p                    = 1.0 1.0
annealing								 = single
annealing_npoints				 = 15
annealing_time					 = 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
annealing_temp					 = 370 365 360 355 350 345 340 335 330 325 320 315 310 305 300
gen_vel                  = yes
gen_temp                 = 300
gen_seed                 = 173529
constraints              = all-bonds


Thanks!

Regards!
                    
Sincerely,

Rongliang Wu
State Key Laboratory
of Polymer Physics and Chemistry
Center of Molecular Science
Institute of Chemistry
Chinese Academy of Sciences
 				

　　　　　　　　　　wurl04 at iccas.ac.cn
　　　　　　　　　　2005-11-30