1Σu and 1Πu states of the hydrogen molecule: Nonadiabatic couplings and vibrational levels

Nonadiabatic coupling matrix elements are computed for six lowest 1Σu+ and four lowest 1Πu electronic states of H2 in a wide range of internuclear distances. These matrix elements are used together with the adiabatic potentials to determine the bound ro-vibrational levels of the 10 electronic states for rotational quantum numbers J ⩽ 10. The computed energies agree quite well with existing experimental term values. However, some of the experimental levels should be assigned differently.