On the binding energy of the ground state of Be 2

Abstract

The binding energy of the beryllium dimer in the ground state is calculated by an extended geminal model. Compared with a full CI calculation for the valence electrons, adding core-valence intersystem correlation terms yields an increase in the binding energy of approximately 0.28 kcal mole , while core-valence intrasystem correlation reduces the binding energy by approximately 0.04 kcal mole . With a basis set of (8s, 5p, 2d, 1f) contracted GTOs on each atom, the extended geminal model yields a binding energy of 2.10 kcal mole and an equilibrium bond length of 4.73 au.