Application of Many-Body Perturbation Theory to the Hydrogen Molecule

Abstract

The hydrogen molecule total energy, polarizabilities, and electron‐coupled nuclear spin‐spin Fermi interaction are studied by many‐body perturbation theory. Two potentials, the Hartree and Hartree–Fock, are considered. Through second order the energies are within several kilocalories per mole of the accurate nonrelativistic values. The Hartree–Fock expansion is reasonably accurate through first order for polarizabilities and gives very good agreement with experiment if a rather simple geometric approximation is used. For the spin–spin coupling constant, good agreement with experiment is obtained using the Hartree potential and considering some second‐ and higher‐order diagrams.