[gmx-users] pressure scaling

Mungikar, Amol Arvind (UMR-Student) mungikar at umr.edu
Sun Mar 14 18:46:01 CET 2004

Few questions and suggestions ----
1. Check for the initial box configuration! how are u generating the initial configuration!!
2. Knowing the exact density you can use 'editconf -density ' option to get the exact density
3. Also, try several values of 'tau_p' before settling with one particular value.
4. Do you think berendesen coupling would be good in this case!
I hope this helps!

	-----Original Message----- 
	From: gmx-users-admin at gromacs.org on behalf of sadhna 
	Sent: Sun 3/14/2004 5:36 AM 
	To: gmx-users at gromacs.org 
	Subject: [gmx-users] pressure scaling

	hi all,
	       I am doing high temperature simulations(400k) at constant
	pressure(15bar, to keep water in liquid state)
	the parameters in mdp file are:
	Pcoupl                   = Berendsen
	Pcoupltype               = Isotropic
	tau_p                    = 1.0
	compressibility          = 4.5e-5
	ref_p                    = 15.0
	i varied 15 to 25 bars am geeting same kind of results
	step 61 Warning: pressure scaling more than 1%, mu: 1.03451 1.03451
	Step 62  Warning: pressure scaling more than 1%, mu: 1.21326e+09
	1.21326e+09 1.21326e+09
	Warning: 1-4 interaction at distance larger than 1
	step 63 Warning: pressure scaling more than 1%, mu: inf inf inf
	Warning: Only triclinic boxes with the first vector parallel to the x-axis
	and the second vector in the xy-plane are supported.
	         Box (3x3):
	            Box[    0]={         nan,          nan,          nan}
	            Box[    1]={         nan,          nan,          nan}
	            Box[    2]={         nan,          nan,          nan}
	         Can not fix pbc.
	Sadhna Joshi
	Research Scholar
	Dept of Chemical Engg
	Indian Institute of Technology,Powai
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