[gmx-users] wierd pressure!

[David van der Spoel]

Rongliang Wu wrote:
> 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.
And what should it be?

> 
> 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
> 
> 
> ------------------------------------------------------------------------
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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