Ab initio calculations of electronic spectra of H2S and H2S2 Original Research Article

The photoelectron and electronic absorption spectra of hydrogen sulfide and dihydrogen disulfide were calculated at the MP2 and Cl ab initio levels. A preliminary study of H2S was performed to optimize our calculations towards a convenient choice of an atomic orbitals basis set: f polarization orbitals were necessary for a good description of the π lone pair of the sulfur atom. The VUV spectrum of H2S was recorded up to 12 eV and agrees well with experimental and previously calculated data. Concerning the dihydrogen disulfide system, the last two molecular orbitals are degenerate for a dihedral angle equal to 90.8° and are very sensitive to it. We propose an interpretation of its photoelectron and VUV spectrum (up to 9 eV) and an extrapolation of the Rydberg spectrum via a set of calculated quantum defects of sulfur.