Theoretical study of Li2H. III. Approximate natural orbital contour diagrams and occupation numbers for the formation and dissociation of Li2H

Approximate natural orbital contour diagrams and occupation numbers are used to analyze ab initio potential energy curves along pathways that lead to the formation and dissociation of Li2H : H + Li2 → Li2H → LiH + Li. In addition to the ground state, the three lowest excited states are analyzed. The analysis revealed extensive charge transfer intermediates of the type Li2 + H-. The species LiH-. . .Li+ w was also found to be an intermediate. The natural orbital description predicts in general that charge transfer is more gradual than is expected on the basis of uncorrelated molecular orbitals. However, rather abrupt natural orbital charge transfer was also encountered