VMD-L Mailing List

From: Mayne, Christopher G (cmayne2_at_illinois.edu)
Date: Wed Jul 24 2013 - 04:22:18 CDT

Francesco,

In my experience, the accuracy gained by using the MP2 method over standard RHF is context/structurally dependent; however, I have observed many cases in which the fine detail of low energy states within a torsion (the important ones during simulation) are only recovered from the higher level of theory. This is also the level of theory prescribed by the authors of CGenFF, so it's what ffTK defaults to. Perhaps others have additional experiences and comments.

Regards,
Christopher Mayne

On Jul 22, 2013, at 11:24 AM, Francesco Pietra wrote:

> Hello:
> Has anyone compared the quality of overall results in carrying out
> FFTK "ScanTorsions" at RHF/6-31* or at default MP2/6-31*? Using
> gamess-us, as I do, the results are extremely similar in terms of
> resulting dihedral, while nearly x 30 faster. I did not carry out any
> other comparison.
> thanks
> francesco pietra