Hi, I hope someone can help me. I have a system of two radical species, and I would like to approximate the energy associated with non-covalent interaction. The molecules are ions, one is cationic, the other anionic. They are are composed of carbon and heteroatoms such as oxygen, nitrogen.

I read about the ENPART function in the manual, but I cannot get it to work for my system. I do not know how to specify the system to be two separate radicals while performing geometry optimization also between the species.

Can someone point me in the right direction?