[gmx-users] Treating electrostatics and van der Waals interactions differently

[David van der Spoel]

On 2013-03-15 19:27, Jeff Woodford wrote:
> Hi all,
> I am attempting to simulate a system that has strong ionic character so I would like to treat the electrostatics and van der Waals interactions separately.  For example I would like to include all pairs of atoms in the electrostatics calculation but I would like to exclude 1-2 and 1-3 neighbors in the van der Waals calculation.  Is this possible to do in GROMACS?  If so, how might this be accomplished?  Thanks in advance for your help.
>
> Jeff Woodford
> Assistant Professor of Chemistry
> Missouri Western State University
>
>
>
In a molecular system you can do this by adding the 1-2 and 1-3 
interactions as pairs, assuming the list of interactions is fixed, like 
in a crystal. Then you can make the LJ parameters different from the 
default and scale the charges down. You probably want to use PME for 
electrostatics. Check the manual!

-- 
David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205.
spoel at xray.bmc.uu.se    http://folding.bmc.uu.se