[gmx-users] Re: Impuls

[David van der Spoel]

On Fri, 9 Nov 2001, Gunnar Karlsson wrote:

>Hi!
>
>I have a question:
>
>Is there an option or a method to control the impulse of a system,
>so that the system is stationary?

yes
nstcomm = 1
this means Number of STeps Center Of Mass Motion.

If you set it to 1, then the total momentum will be subtracted at each
step. If you set it to -1 then the rotational momentum will also be
subtracted (but this is not very exact and does not work in parellell).

You can even have different groups for center of mass motion, which can be
interesting if you do very long simulations. In this case your center of
mass motion groups should be the same as your temperature coupling groups
(although that is not enforced).

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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