Theoretical investigation of PH(X3Σ−) radical: Analytic potential energy function, spectroscopic parameters and vibrational manifolds (J = 0)

The coupled-cluster singles-doubles-approximate-triples [CCSD(T)] theory in combination with the correlation-consistent quintuple basis set augmented with diffuse functions (aug-cc-pV5Z) is used to investigate the spectroscopic properties of the PH(X 3Σ−) radical. The adiabatic potential energy curve is calculated over the internuclear separation ranging from 0.06 to 2.10 nm and is fitted to the analytic Murrell-Sorbie function, which is employed to determine the spectroscopic parameters, ωeχe, αe and Be. The present De, Re, ωe, ωeχe, αe and Be values are of 3.1617 eV, 0.14239 nm, 2368.475 cm−1, 44.8679 cm−1, 0.2548 cm−1 and 8.5187 cm−1, respectively, which are in excellent agreement with the available experiments. With the potential obtained at the UCCSD(T)/aug-cc-pV5Z level of theory, the total of 18 vibrational states is predicted when 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 reproduced for the PH(X 3Σ−) radical when J = 0 for the first time, which are in good accord with the available measurements.