[gmx-users] soft-core potential in combination with PME (sorry, again)

[Maik Goette]

David Mobley wrote:

 > If I remember correctly, basically what the Anwar paper tries to
 > achieve is separately smoothing the two. You could probably accomplish
 > the same thing by allowing separate sc-alpha and sc-power for Coulomb
 > and LJ interactions so they can be tuned separately.

I would suggest to implement exactly that in the version 4.
As David mentioned, there CAN occur problems with the differing 
parameters. In contrast to David, I experienced no general benefit in 
using different parameters for coulomb and vdw, what may be somehow my 
fault, or, more likely (maybe also less ;) ), depend on the system one 
perturbs.

If you would change the code somehow, that the parameters can be 
modified independendly, I would also suggest to implement a sort of 
sigmoidal behaviour for the lambda change.
We did that for the 3.3.1 code, so I could, at least, provide you with 
the basic code for that.

Regards

Maik Goette, Dipl. Biol.
Max Planck Institute for Biophysical Chemistry
Theoretical & computational biophysics department
Am Fassberg 11
37077 Goettingen
Germany
Tel.  : ++49 551 201 2310
Fax   : ++49 551 201 2302
Email : mgoette[at]mpi-bpc.mpg.de
         mgoette2[at]gwdg.de
WWW   : http://www.mpibpc.gwdg.de/groups/grubmueller/