Investigations on spectroscopic properties of SiH(X 2Π) radical using coupled-cluster theory in combination with the correlation-consistent quintuple basis set

Abstract

The coupled-cluster singles-doubles-approximate-triples [CCSD(T)] theory in combination with the correlation-consistent quintuple basis set (aug-cc-pV5Z) is used to investigate the spectroscopic properties of the SiH(X 2Π) radical. The adiabatic potential energy curve is calculated over the internuclear separation range from 0.09 to 2.51 nm and is fitted to the analytic Murrell–Sorbie function, which is employed to accurately calculate the spectroscopic parameters, ω eχ e, α e and B e. The present D e, R e, ω e, ω eχ e, α e and B e results are of 3.1806 eV, 0.15223 nm, 2046.914 cm −1, 36.7711 cm −1, 0.2178 cm −1 and 7.4779 cm −1, respectively, which are in excellent agreement with the experimental findings. With the potential obtained at the CCSD(T)/aug-cc-pV5Z level of theory, a total of 21 vibrational states is found when J = 0 by numerically solving the radial Schrödinger equation of nuclear motion. For each vibrational state, the vibrational level, classical turning points, inertial rotation constant and centrifugal distortion constants are reported for the first time.