Potential-Energy Curve for the <i>B</i> 1Σ<i>u</i>+ State of the Hydrogen Molecule

Abstract

An accurate potential-energy curve for the B 1Σu+ state of H2 has been computed using variational wavefunction in the form of an expansion in elliptic coordinates and depending explicitly on the interelectronic distance. The theoretical clamped-nuclei binding energy (De=28 896.3 cm−1) with diagonal corrections for nuclear motion (ΔD=−46.1 cm−1) gives the adiabatic binding energy De=28 850.2 cm−1 in a good agreement with the experimental value De=28 852.8 cm−1. However, for small and large values of the internuclear distance, the theoretical potential-energy curve very significantly differs from the corresponding RKR curve. The computed wavefunctions are analyzed in terms of some simple functions and it is shown that for 3&amp;lt;R&amp;lt;7 a.u. the B state is predominantly ionic in character.