Spectroscopic investigations on BH~+(X~2∑ ~+) ion using MRCI method and correlation-consistent sextuple basis set augmented with diffuse functions

摘要

The highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in combination with a series of correlation-consistent basis sets, cc-pVnZ and aug-cc-pVnZ (n = 2, 3, 4, 5, 6), in the valence range is employed to investigate the equilibrium internuclear separations, harmonic frequencies and potential energy curves (PECs) of the BH~+(X~2∑~+) ion. The PECs are all fitted to the Murrell-Sorbie function, which are used to reproduce the spectroscopic parameters, such as D_e, ω_eπ_e, α_e, B_e, and D_0. By comparison with the available experiments, The PEC, which is determined at the sextuple basis set augmented with diffuse functions, aug-cc-pV6Z, is found to most suitably determine the spectroscopic properties of the ground-state BH~+ ion. The D_0, D_e, R_e, ω_e, ω_eπ_e, α_e, and B_e at this basis set are of 1.9823 eV, 2.1364 eV, 0.12041 nm, 2520.81 cm~(-1), 61.80 cm~(-1), 0.4824 cm~(-1), and 12.5932 cm~(-1), respectively, which are in excellent agreement with the available measurements. With the interaction potential determined at the MRCI/aug-cc-pV6Z level of theory, by numerically solving the radial Schr?dinger equation of nuclear motion using the Numerov method, the total of 16 vibrational states is predicted when the rotational quantum number J is equal to zero (J = 0). The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J = 0 for the first time, which agree well with the available experiments.