ON THE CONTRIBUTION OF THE POLARIZATION ENERGY TO THE CHEMICAL-BOND IN H-2

The polarized wavefunction obtained from the Rayleigh-Schrodinger perturbation theory (without symmetry) is used to approximate Herring's localized wavefunction of the H-2 molecule. An explicit expression is derived for the energy to which the polarization series converges. It is equal to the ground-state energy at the united-atom limit and to the Coulomb energy at large internuclear distances where the overlap can be neglected. With numerical data, it is shown that the polarization energy converges rather rapidly toward this limit for all internuclear distances, including the region of the chemical bond.