Specifying multiple charges for the same atom, pair_coul_long

Forgot to cc the list.

Forgot to cc the list.

Thank you for the quick reply. I agree that coupling random interactions
from different force fields is indeed incorrect. Perhaps I should have been
more clear and more specific.

I'm trying to model interactions of co2 is flexible zeolite frameworks.
The zeolite dynamics are defined using the class2 hill-sauer FF for which
the charges are, say 0.5 (Si) and -0.25 (O). The FF also has the class2
bonded interactions and lj dispersion. This FF by itself is consistent and
gives correct zeolite dynamics.

Now, let's move on to co2. For the co2 molecule to be correctly modeled,
the zeolite charges of 0.5 and -0.25 are incorrect. Instead, based on DFT
FFs, charges of 2 and -1 correctly partition the dispersion and coul
interactions. Thus, the co2 zeolite FF is consistent and predicts adsorption

Now, I need to include the effects of framework flexibility (hill sauer)
with co2 interactions (DFT FF). Thus, it is necessary to have separate
charges on the Si and O atoms for co2 and framework dynamics respectively.

Does this make more sense?

no. all you have done is describe the origin of the inconsistency.

you have to reparametrize your CO2. for the most part, this is just a
scaling factor, however, you also need to take into account that
class2 is softer on the repulsive branch of the LJ interactions, which
is perfectly in keeping with a reduction of the charges.