THEORETICAL-STUDY OF SI2HN (N=0-6) AND SI2HN+ (N=0-7) - APPEARANCE POTENTIALS, IONIZATION-POTENTIALS, AND ENTHALPIES OF FORMATION

The Gaussian-2 (G2) theoretical procedure, based on ab initio molecular-orbital theory, is used to calculate the energies of Si2H(n) (n = 0-6) and Si2H(n)+ (n = 0-7). The resulting G2 energies are used to calculate appearance potentials and ionization potentials. The results are in general agreement with the recent photoionization studies of Ruscic and Berkowitz [J. Chem. Phys. 95, 2407 (1991); 95, 2416 (1991)], supporting their observation of the species Si2H2, Si2H3, Si2H4, and Si2H5 for the first time. Atomization energies of the neutrals are calculated and used to derive enthalpies of formation. In most cases the results are in good agreement with previous theoretical values. In addition, new results for the structures of Si2H6+, Si2H3, and Si2H+, the enthalpies of formation of the cations, and proton affinities are presented.