Hello,

I would like to ask a question regarding the mixing rules for Lennard-Jones interactions between 1-4 atoms. I am currently examining polyaromatic molecules grafted with aliphatic side chains and want to model them using CGenFF. As a result, in my simulations, two major atom types are the CG2R61 and CG321 types.

In the CGenFF prm file, one finds the following LJ entries regarding the aforementioned atom types:
CG2R61 0.0 -0.0700 1.9924
CG321 0.0 -0.0560 2.0100 0.0 -0.01 1.9

From what I understand, when two CG2R61 atoms are 1-4 neighbors, the values epsilon=-0.0700 and sigma=1.9924 are used without scaling and when two CG321 atoms are 1-4 neighbors, the values epsilon=-0.01 and sigma=1.9 are used; also unscaled.

What happens in the case of a CG2R61-CG321 1-4 pair? Are the parameters (-0.0700, 1.9924) and (-0.01, 1.9) combined via typical Lorentz Berthelot mixing?

I appreciate any input on this subject.

Thanks in advance.