Electric properties of diatomic interhalogens. A study of the electron correlation and relativistic contributions

Abstract

The recently developed polarized basis sets for halogen atoms are used to calculate several basic electric properties of diatomic interhalogen molecules. In the valence approximation the electron correlation contribution is treated at the level of the fourth-order many-body perturbation theory approximation. The corresponding results are corrected for the core-polarization and relativistic effects. It is shown that the dipole moments of heavy interhalogen diatomics are considerably affected by the relativistic contribution, while the core-polarization effects are of lesser importance. The calculated, relativistically corrected, dipole moments are in agreement with experimental data and are used to discuss the reliability of the effective core potential approximation. The calculated quadrupole moments and parallel components of the dipole polarizability tensor are only marginally affected by contributions due to core-polarization and relativistic terms. The geometry derivatives of dipole moments and dipole polarizabilities computed in this study can be used for the evaluation of intensities in infrared and Raman spectra of interhalogen diatomics.