Ab initio electron affinities of AlH, SiH, GaH, and GeH, including characterization of bound excited states of SiH- and GeH-

Ab initio benchmark calculations are reported for the diatomic hydrides of Al, Si, Ga, and Ge and their negative ions using correlation consistent bas is sets and several correlated methods. Adiabatic electron affinities for t he 0-0 transition were found to be 0.193, 1.256, 0.131, and 1.251 eV for AM , SiH, GaH, and GeH, respectively, at the RCCSD(T)/aug-cc-pVQZ level of the ory. Excitation energies (TO) of the a(1)Delta and b(1)Sigma (+) bound exci ted states were found to be 0.560 and 1.017 eV for SiH- and 0.595 and 1.026 eV for GeH- at the MRCI + Q/aug-cc-pVQZ level. Selected spectroscopic cons tants are reported for the eight negative ion states, (C) 2001 Elsevier Sci ence B.V. All rights reserved.