[gmx-users] epsilon_r question

David van der Spoel spoel at xray.bmc.uu.se
Thu Mar 14 23:43:45 CET 2002

On Thu, 14 Mar 2002, Rui Qiao wrote:

>Hi *:
>	I want to do a simulation where ions are moving in some medium
>with a diaelectric constant of 25. I want to use PME for the
>electrostatics, but I am wondering if I can turn the epsilon_r = 25 and go
>ahead with PME.
>	My concern is that perhaps such epislon_r is implemented only for
>the cut-off scheme? (maybe I am murming nosense...).
This is correct. It seems like you want to simulate the ions in some ind
of continuum (implicit) solvent is that right? Maybe using langevin

In that case you could just divide all the charges by 5, and use PME for
the same effect. 

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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