Binding Energy of LiH+ and the Ionization Potential of LiH: Mixed Basis Set Calculation

Abstract

A rigorous lower bound of 0.038 eV for the binding energy of LiH⁺ has been obtained via an ab initio quantum mechanical calculation using a generalized valence‐bond wavefunction with a mixed basis set of elliptic and Slater‐type orbitals. The probable error in the total energy given by this calculation is of the order of 0.1 eV, so that a probable upper bound for the binding energy of LiH⁺ is 0.15 eV. This invalidates the conclusion of a previous SCF—MO calculation which gave a substantial minimum in the LiH⁺ potential curve. A rigorous upper bound of 7.91 eV for the ionization potential of LiH is found by the relation E(LiH⁺, calculated) — E(LiH, experimental) ≥I.P. (LiH). A probable lower bound for I.P. (LiH) is 7.8 eV. Potential curves for the system Li⁺+H from several wavefunctions are tabulated.