[gmx-users] correction in oplsaa to rb conversion?

[David van der Spoel]

gil claudio wrote:
> I just derived the conversion of the dihedral
> constants from OPLSAA to RB and I get a set of
> equations different from the ones printed in the
> manual (3.3, p 56).
> 
> C1 = V1 / 2 - 3 V3 / 2
> C3 = 2 V3
> 

> These are the negative of what is printed in the
> manual.

I think you're right. Question now is what was used in the derivation of 
the parameters? Erik, can you comment?

Also the reference (60) is incorrect, it should be
Jorgensen, J. Phys. Chem. 90 (1986) 1276

Finally, do also note that in the latest OPLS paper
Jorgensen & Tirado-Rives J. Comp. Chem. 26 (2005) 1689
a further term is introduced in the torsion function. This is not yet 
used in GROMACS AFAIK.


> 
> The rest are the same.  I'd like to know if what I did
> was correct. I can send the mathematica file to those
> interested in the derivation.
> 
> Gil Claudio
> University of Asia and the Pacific
> 
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-- 
David.
________________________________________________________________________
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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