Ab initio calculation of molecular hydrogen electronic states’ properties: fine structure spin–spin constants

Abstract

The aim of this work is the ab initio study of the properties of the electronically excited states of the H2 molecule for progressively higher states. Computations are performed using the recent DYCI code developed by Mitrushenkov. The DYCI code allows the very accurate calculation of the energies of molecular electronic excited states and of their properties such as transition moments, fine structure constants (spin–orbit and spin–spin), non-adiabatic coupling matrix elements. Fine structure spin–spin constants for Rydberg series np3Π u (n = 2,3,4), nd3Π g (n = 3,4,5), nd3Δ g (n = 3,4) and for the first three states have been calculated for a range of internuclear distances spanning 0.6 to 12 bohr. Comparison with available experimental results is provided.