A Møller-Plesset study of the electron affinities of the diatomic hydrides XH (X=Li,B,Be,C,N,O)

Electron affinities for LiH, BeH, BH, CH, NH and OH are computed at the MP2, MP3, and full MP4( SDTQ) order of perturbation theory employing the basis sets 6-31G(d,p), 6-311G(d,p), 6-311++G(d,p), and 6-311++G(3df,3pd), using geometries optimized at MP2/6-31G(d,p). At the MP4(SDTQ)/6-311++G(3df,3pd)//MP2/ 6-31G(d,p) level including zero-point corrections, electron affinities are predicted with a maximum deviation of 0.2 eV from experiment. At the same level of theory, dissociation energies of the anions are computed to an accuracy of 0.11 eV. The energy results reported here are in most cases in better agreement with experiments than previous theoretical results. Vibrational frequencies and atomic distances are determined at the MP2/6-31G(d,p) level indicating longer bonds and lower frequencies as a consequence of electron attachment to the neutral hydrides.