Total electrostatic interaction energy between two given atomic species

Definition:

A – given atomic species

B – another atomic species

E_ee(AB)- electronic repulsion energy between two atomic species

E_ne(AB)- electron-nuclear attraction energy between two atomic species

E_nn(AB)- nuclear repulsion energy between two atomic species

Reference:

1. E. Clementi, Computational Aspects of Large Chemical Systems, Springer Verlag, New York, 1980.