Theoretical study on the vibrational spectra and potential energy curves for SiC ([formula omitted]) and SiS ([formula omitted]) molecules

Abstract

In this work, the vibrational constants (ωe,ωexe) calculated by the variational algebraic method (VAM) and some other molecular constants (De,re,Be,αe) were used to construct the improved Hulburt–Hirschfelder (IHH) analytical potential energy function (APEF). Not only that, but the calculated VAM potential points are used as the ’true’ energies to determine the value of the variational parameter λ which is the pivotal fitting parameter in the IHH potential. With limited experimental data, high-precision IHH potential can be achieved by combining the VAM and the IHH APEF. This combination of the VAM and the IHH APEF is referred to be VAIHH APEF, which is employed to study the vibrational energies and potential energy curves (PECs) of SiC (X3Π) and SiS (X1Σ+) molecules, yielding full vibrational spectra and spectroscopic constants. The calculational results indicate that the VAIHH APEFs of SiC (X3Π) and SiS (X1Σ+) molecules are in good agreement with the experimental RKR potential points. Accurate PECs of SiC (X3Π) and SiS (X1Σ+) molecules imply that the VAIHH APEF is of high quality.