POTENTIAL-ENERGY SURFACES OF EXCITED-STATES OF H-2(-)

Thirteen electronic states of H-2(-) in various symmetries have been c alculated using the MRCI/aug-cc-pV5Z approximation. The lowest 2 Sigma (u)(+) and (2) Sigma(g)(+) states have been shown to cross with the X- 1 Sigma(g)(+) state of H-2 at the nuclear separation of 1.58 and 2.70 Angstrom and the energies of 3.16 and 4.66 eV, respectively. The surfa ces of higher excited states exhibit complex shapes defined by avoided crossings between the states of the same symmetry. Some of the excite d H-2(-) and H-2 surfaces cross, and this crossing can be relevant to the electron attachment processes in laser-irradiated H-2. (C) 1998 El sevier Science B.V.