AB-INITIO CALCULATIONS OF ELECTRONIC-SPECTRA OF H2S AND H2S2

The photoelectron and electronic absorption spectra of hydrogen sulfid e and dihydrogen disulfide were calculated at the MP(2) and CI ab init io levels. A preliminary study of H2S was performed to optimize our ca lculations towards a convenient choice of an atomic orbitals basis set : f polarization orbitals were necessary for a good description of the pi lone pair of the sulfur atom. The VUV spectrum of H-2 was recorded up to 12 eV and agrees well with experimental and previously calculat ed data. Concerning the dihydrogen disulfide system, the last two mole cular orbitals are degenerate for a dihedral angle equal to 90.8 degre es and are very sensitive to it. We propose an interpretation of its p hotoelectron and VUV spectrum (up to 9 eV) and an extrapolation of the Rydberg spectrum via a set of calculated quantum defects of sulfur.