Double Configuration Self-Consistent Field Study of the Πu1, 3Πu, 1Πg and Πg3 States of H2

Abstract

Complete potential energy curves for the four lowest‐lying Π states of the hydrogen molecule are calculated using an hierarchy of one‐ and two‐configuration model wavefunctions: the Hartree–Fock model, the configuration interaction model, and the optimal double configuration model (a double configuration SCF model). Comparison and evaluation of the three models are given as a function of internuclear separation of the nuclei for the 1 Π u state. An extended basis set of 10 Slater‐type orbitals on each nucleus is scaled optimally for the 1 Π u state; the spectroscopic constants for this state are in excellent agreement with experiment. The basis set used for the 1 Π u state is employed in determining the potential energy curves for the 3 Π u , 1 Π g , and 3 Π g states; the 3 Π u state shows good agreement with experiment, and the essential features for the Π g states are characterized properly.