[gmx-users] Going from OPLS-AA dihedrals to CHARMM22 dihedrals.

[Dawid das]

Dear Gromacs experts,

I have following issue. I need torsional parameters from this publication:
D. V. Dmitrienko et al., Biochemistry (Moscow), 2006, Vol. 71, No. 10,
1133-1152
where OPLS-AA FF has been used but I need to adapt them for CHARMM22 FF.
Now the thing is that there are two different torsional energy expression
used in those FFs.
How can I go from one to another?
To be precise I want to adapt parameters from the above mentioned
publication to expression  for torsional potential from this publication:

N. Reuter et al., J. Phys. Chem. B, 2002, Vol. 106,  6310-6321

Any help will be appreciated.

Best wishes,

Dawid Grabarek