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

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 D0. The present D0, De, Re, ωe, ωeχe, αe and Be obtained at the cc-pV5Z basis set are of 2.8004 eV, 2.9351 eV, 0.15137 nm, 2194.341 cm−1, 43.1235 cm−1, 0.2031 cm−1 and 7.3980 cm−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.