Single-centre molecular orbital calculations on third row hydrides–SeH2 and HBr

Single-centre molecular orbital calculations are reported for SeH2, and HBr using basis sets extending up to 5d orbitals centred on the heavy atoms. The choice of orbitals to be used in extending the basis set and the optimum values for orbital exponents are discussed. Orbital energies comparable with minimal basis set multicentre calculations are obtained for SeH2. The orbital energies are compared with those obtained experimentally by photoelectron spectroscopy. The results suggest that the single-centre method is worthy of consideration when studying the hydrides of the heavier elements.