From: Gumbart, JC (
Date: Mon Jan 27 2020 - 19:52:53 CST

Hi David,

You should look carefully at the dihedral scan that gives the anomalously low values. There is probably some interaction that is too favorable, possibly due to unrealistic charges. If you suspect that, you can modify the charges to see if it makes a difference.


On Jan 25, 2020, at 12:07 AM, David Sáez <<>> wrote:

Hello everyone,

I am working on the parametrization of a small molecule using the superb tool called FFToolkit and Gaussian 16. Up to now, it has worked great. Now, in the dihedral section I am facing problems. When trying to find parameters to reproduce the QM potential, I get this plot:

Is it normal for the preliminary MM potential to be so high in comparison to the QM potential? Should I take a look on the other elements of interaction (charges, angles, bonds) because they could be raising the energy too much?

Thanks for your time.