An improved determination of the equilibrium structure and molecular properties of XBS and XCP (X = H, F, Cl) molecules from ab initio calculations

Abstract

The availability of core-valence basis sets for second-row atoms together with highly accurate coupled-cluster calculations allow us to present an improved determination of the equilibrium structure of the XBS and XCP (X = H, F, Cl) molecules. Core correlation effects and basis set incompleteness have been taken into account in order to obtain best estimates of their equilibrium geometries: results which can be quantitatively compared to experiment are reported. In addition, two important molecular properties, namely the dipole moment and the nuclear quadrupole coupling constants, have been investigated. The molecular dipole moment has been calculated at coupled-cluster level using bases of different quality including diffuse functions and taking into account both core correlation effects and basis set incompleteness. The quadrupole coupling constants, evaluated from the electric field gradient at the quadrupolar nuclei, have been computed at the multi reference configuration interaction, Møller–Plesset perturbation to second order, and coupled-cluster levels of theory employing large core-valence basis sets.