Nuclear-electron attraction energy between two givenatoms

Definition:

A – given atomic species

B – another atomic species

P- density matrix elements over atomic basis {}

Z_B - charge of atomic nucleus, B

R_iB - distance between the electron and atomic nucleus, B

 - electron-nuclear attraction integrals on atomic basis {}

Reference:

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