AsH3 ultraviolet photochemistry: An ab initio view

Multireference configuration interaction calculations have been carried out for low-lying electronic states of AsH3. Bending potentials for the nine lowest states of AsH3 are obtained in C-3v symmetry for As-H distances fixed at the ground state equilibrium value of 2.850 a(0), as well as for the minimum energy path constrained to R-1 = R-2 = R-3. The calculated equilibrium geometry and bond energy for the (X) over tilde (1)A(1) ground state agree very well with the previous experimental and theoretical data. It is shown that the lowest excited singlet state belongs to the (1)A(1) symmetry (in C-3v), in contradiction to the previous calculations. This state is characterized by a planar equilibrium geometry. Asymmetric stretch potential energy surface (PES) cuts along the H2As-H recoil coordinate (at R-1 = R-2 = 2.850 a(0), theta = 123.9 degrees and 90 degrees) for numerous excited states and two-dimensional PESs for the (X) over tilde and (A) over tilde states up to the dissociation limits are obtained for the first time. The (A) over tilde (1)A(1), (B) over tilde E-1 - (X) over tilde (1)A(1) transition moments are calculated as well and used together with the PES data for the analysis of possible photodecay channels of arsine in its first absorption band. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4727851]