Potential energy surfaces of excited states of H 2−

Abstract

Thirteen electronic states of H 2 − in various symmetries have been calculated using the MRCI/aug-cc-pV5Z approximation. The lowest 2Σ u + and 2Σ g + states have been shown to cross with the X 1Σ g + state of H 2 at the nuclear separation of 1.58 and 2.70 Å and the energies of 3.16 and 4.66 eV, respectively. The surfaces of higher excited states exhibit complex shapes defined by avoided crossings between the states of the same symmetry. Some of the excited H 2 − and H 2 surfaces cross, and this crossing can be relevant to the electron attachment processes in laser-irradiated H 2.