Ab initio calculations of the electronic states of AsH2 including dissociation characteristics

Multireference configuration interaction calculations have been carried out for low-lying electronic states of AsH(2). Bending potentials for the ten lowest states of AsH(2) are obtained in C(2v) symmetry for As-H distances fixed at the the ground state equilibrium value of 2.845 a(0), as well as for the minimum energy path constrained to R(1) = R(2). The calculated equilibrium geometries for the X̃(2)B(1) ground state and the Ã(2)A(1) excited state agree very well with the previous experimental and theoretical results, whereas the data for the higher-lying states are obtained for the first time. Asymmetric potential energy surface (PES) cuts (at R(1) = 2.845 a(0), θ = 90.7°) and two-dimensional (2D) PESs for the lowest three states are also new. The calculated ab initio data are used for analysis of possible AsH(2) photodissociation channels and predissociation effects. It is shown that the Ã(2)A(1)-X̃(2)B(1) transition dipole moment decreases with increasing bending angle, which influences the intensity distribution in the Ã(0,0,0)→X̃ emission spectrum (v(2)'' bending series), shifting its maximum to smaller v(2)'' quantum numbers.