Spectroscopic investigations on AsH(X3Σ−) radical using CCSD(T) theory in combination with correlation-consistent quintuple basis set

Abstract: The equilibrium internuclear separations, harmonic frequencies and potential energy curves of the AsH(X3Σ − ) radical have been calculated using the coupled-cluster singles–doubles–approximate-triples [CCSD(T)] theory in combination with the series of correlation-consistent basis sets in the valence range. The potential energy curves are all fitted to the Murrell–Sorbie function, which are used to reproduce the spectroscopic parameters such as De , ωeχe , αe , Be and D 0. The present D 0, De , Re , ωe , ωeχe , αe and Be obtained at the cc-pV5Z basis set are of 2.8004eV, 2.9351eV, 0.15137nm, 2194.341cm − 1, 43.1235cm − 1, 0.2031cm − 1 and 7.3980cm − 1, respectively, which almost perfectly conform to the measurements. With the potential obtained at the UCCSD(T)/cc-pV5Z level of theory, a total of 18 vibrational states is predicted when the rotational quantum number J is set to equal zero (J =0) by numerically solving the radial Schrödinger equation of nuclear motion. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J =0 for the first time, which are in excellent agreement with the experiments. [Copyright &y& Elsevier]