Configuration Interaction Applied to the Hydrogen Molecule

Abstract

The electronic wave function for the hydrogen molecule has been described as a sum of three configurations, each of which is expressed in terms of one-electron symmetry orbitals, which are written as variational functions of the elliptic coordinates. To a state due to Coulson, made up of orbitals which are individually even under inversion, we first added an odd-odd state, thus improving the computed binding energy from 3.535 ev to 4.125 ev. The addition of a third state, of a somewhat different character, increases the binding energy to 4.276 ev. The experimentally observed binding energy is 4.72 ev. The role of the several configurations is explained in terms of the concept of spatial correlation, following the work of Lennard-Jones and co-workers.