Vibrational Frequencies and Spectroscopic Constants for 1 3A′ HNC and 1 3A′ HOC+ from High-Accuracy Quartic Force Fields

Abstract

The spectroscopic constants and vibrational frequencies for the 1 (3)A' states of HNC, DNC, HOC(+), and DOC(+) are computed and discussed in this work. The reliable CcCR quartic force field based on high-level coupled cluster ab initio quantum chemical computations is exclusively utilized to provide the anharmonic potential. Then, second-order vibrational perturbation theory and vibrational configuration interaction methods are employed to treat the nuclear Schrödinger equation. Second-order perturbation theory is also employed to provide spectroscopic data for all molecules examined. The relationship between these molecules and the corresponding 1 (3)A' HCN and HCO(+) isomers is further developed here. These data are applicable to laboratory studies involving formation of HNC and HOC(+) as well as astronomical observations of chemically active astrophysical environments.