[gmx-users] T-coupling/freeze groups

David van der Spoel spoel at xray.bmc.uu.se
Wed Apr 17 20:45:22 CEST 2002

On Wed, 17 Apr 2002, Rainer Boeckmann wrote:

>simulating a large water box at 1000bar with a numer of atoms (1000) freezed I
>get a continuous temperature increase of 4K during 10ps after switching off the
>temperature coupling. For the freezed atom group the non-bonded interactions are
>additionally excluded. Does anyone know about the source of this temperature
Check a few things please:
1. Are you using a cut-off? Then you will get large temperature increase
   if you switch off t coupling (also without freezing atoms)
2. Have you defined center-of-mass motion removal group for the frozen 
   atoms? Otherwise they will still move.
3. Is you time step too long (particularly since you run at 1000 bar)?

Groeten, David.
Dr. David van der Spoel, 	Biomedical center, Dept. of Biochemistry
Husargatan 3, Box 576,  	75123 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://zorn.bmc.uu.se/~spoel

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