Configuration interaction study on the low-lying electronic states of indium antimonide

Abstract

Large scale ab initio based multireference singles and doubles configuration interaction calculations have been performed to investigate the spectroscopic properties of the low-lying electronic states of indium antimonide (InSb). Relativistic effective core potentials and spin–orbit operators are used for this purpose. Potential energy curves of Λ-S states which correlate with lowest three dissociation limits are also computed. The ground state X3Σ−of InSb is dominated by the …σ2π2 configuration with re=3.02Å and ωe=139cm−1. The ground-state dissociation energy of InSb has been calculated to be 1.22eV which is somewhat smaller than the re-estimated experimental value of 1.45eV. Effects of the spin–orbit coupling on the spectroscopic parameters and potential energy curves of those states which correlate with the lowest two dissociation limits are studied. The spin–orbit interaction splits the ground state into two components which are 429cm−1 apart. The 0+ component of the ground state lies below the other component with Ω=1. Transition moments of some dipole allowed transitions are computed from configuration interaction (CI) wave functions. Radiative lifetimes of six excited states of InSb are estimated. The A3Π state is short-lived with a lifetime of about 530ns. The A3Π0+ component which does not predissociate undergoes symmetry allowed transitions with ΔΩ=0,1, and the total lifetimes of this state at three vibrational levels v′=0, 1 and 2 lie in the range 2.25–2.5μs.