AMBER Archive (2007)

Subject: AMBER: Dihedral FF parameters

From: FyD (fyd_at_u-picardie.fr)
Date: Fri Jan 19 2007 - 09:40:10 CST

Dear All,

I try to develop a bunch of new FF parameters by fitting MM energies
to QM energies. As first tests, I decided to fit the FF dihedral
parameters to data generated to the B3LYP/6-31+G**/HF/6-31G* &
MP2/6-31+G**//HF/6-31G* theory levels. Since my model is a little big,
I think I cannot afford MP4 energies.

In FF development and to get QM single point energy, what theory level
is the best, I mean for taking into account electron correlation: MP2
or B3LYP ?

I would answer MP2, however I was quite surprised to see that the
B3LYP energies are smaller than the MP2 ones.

Thank you, regards, Francois

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