[gmx-users] A simple question about reaction-field

David van der Spoel spoel at xray.bmc.uu.se
Tue Oct 3 18:29:12 CEST 2006

Alexandre Suman de Araujo wrote:
> I´m performing a simulation of an ion in water (TIP3P) using reaction
> field. I define energy_grps = ion sol in my .mdp file.
> When I use rlist = rcoulomb, no LR terms appear in g_energy list.
> When I use rlist < rcoulomb, these LR terms appear.
> So, the LR terms obtained using reaction field is the contribution of
> implicit solvent between rlist and rcoulomb or the contribution of
> implicit solvent beyond rcloumb, as is said in GMX manual and other
> reference texts?
> Thanks
No, the LR energy is still the directly computed energy between the R*.

The reaction field effect is implicit in the Coulomb potential, except 
when you have larger molecules and an exclusion correction term is added.

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://folding.bmc.uu.se

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