Group V trimers and their positive ions: The electronic structure and potential energy surfaces

摘要

Complete active space multiconfiguration selfhyphen;consistent field (CAShyphen;MCSCF) followed by multireference configuration interactions (MRCI) calculations are made on the electronic states of P3, As3, Sb3, Bi3and all their positive ions. All group V trimers have Jahnhyphen;Teller distorted2A2ground states arising from the2Elsquo;(D3h) state while the positive ions have1Arsquo;1(D3h) equilateralhyphen;triangular ground states. For the neutral species, the2B1Jahnhyphen;Teller component was found to be nearly degenerate with the2A2component. Extensive studies on As3, Sb3, and Bi3reveal the existence of4A2,4Ersquo;, and2Ersquo;(D3h) excited states which also undergo Jahnhyphen;Teller distortion. The binding energies and the ionization potentials (IP) of all group V trimers were computed and compared with known experimental data on some of these species. The IPs and the binding energies per atom of group V trimers were found to be significantly smaller than dimers thus exhibiting oddndash;even alternation in these properties. Our computations explain the dramatically different photofragmentation patterns for antimony and bismuth clusters observed by Geusicetal.