Spectroscopic constants and potential energy curves of GaAs, GaAs +, and GaAs −

Abstract

Twenty electronic states of GaAs, 12 electronic states of GaAs +, and 13 electronic states of GaAs − are investigated using relativistic ab initio complete active space MCSCF (CASSCF) followed by large-scale configuration interaction calculations which included up to 700 000 configurations. Potential energy curves and spectroscopic constants of all these states of three radicals are obtained. Spectroscopic constants of low-lying states of GaAs are in very good agreement with both experiment and all-electron results. Two nearly-degenerate states of 2Σ +, 2Π ( 2Σ + lower) symmetries are found as candidates for the ground state of GaAs −. The GaAs − negative ion is found to be more stable compared to the neutral GaAs ( D e(GaAs −) = 3 eV). The electron affinity of GaAs is computed as 0.89 and 1.3 eV at the FOCI and SOCI levels of theory, respectively. Calculated potential energy curves of GaAs are in accord with the experimentally observed predissociation in the 3Π( III) - X 3 Σ − system.