[gmx-users] Thiophosphate LJ-Parameters

[Maik Goette]

I'm searching for LJ-parameters for a sulphur bound to phophorous in a 
thiophosphate.
I tried some literature search, but didn't find anything, except some 
statement of 1985, that in this case the negative charge is shifted to 
the sulphur (our QM calculations don't agree with that, anyway).
Now, the question arises, which LJ-parameters for sulphur to choose.

In OPLSAA, there are some anionic sulphur LJ-parameters (which are not 
in the amberFF, but I guess, they could simply be ported)...still, I 
don't feel well, using those, because, our QMs clearly show, it's no 
sulphur anion.

Does anyone have any hints towards thiophosphate paramters (literature, 
chemists intuition ;) ), or at least an idea, which amberFF-sulphur I 
can use, without getting in to much trouble?
Furthermore, exactly this sulphur should undergo TI, which even makes 
things worse, concerning correct parameters.

Best 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/