Computational spectroscopy of diatomic tungsten carbide, WC

Abstract

The bond length, electronic term symbols, bond dissociation energies (BDEs), and spectroscopic parameters of numerous low-lying electronic states of diatomic tungsten carbide (WC) have been calculated at a high level of theory. The calculations were done by using the Internally-Contracted multi-reference wave function IC-MRCI/aug-cc-pV5Z(-PP) approach. Davidson corrections were also included using the MRCI + Q method. Zero-point vibrational energy (ZPE) corrections, spin–orbit interactions, and relativistic effects are also included. The bond dissociation energy, equilibrium internuclear distance and the harmonic vibrational frequency of the ground electronic state WC(X3Δ) are computed to be D0 = 5.26 eV, Re = 1.714 Å and ωe = 979 cm−1, respectively. The energies of the lowest vibrational levels (v = 0, 1, 2 and 3) of WC(X3 Δ) are computed to be (0.00, 979.7, 1948.9, 2903.6 cm−1); their rotational constants, Bv, are also computed as (0.50717, 0.50966, 0.49990 and 0.49626 cm−1), respectively. Spectroscopic parameters (ωe, ωexe, Be and αe) and equilibrium bond lengths (Re) for several Λ-S and Ω bound states of WC are also provided in this work. These results are in excellent agreement with the available experimental data.