Electron correlation and relativistic effects in electric properties of the alkali metal fluorides

Abstract

The major electric properties in the series of the alkali metal fluorides are calculated with the purpose of investigating the electron correlation and relativistic contributions. The reported results for KF, RbF, CsF, and FrF correspond to three different levels of approximation concerning the treatment of the electron correlation contribution to the investigated properties. The relativistic effects are studied by using the scalar Pauli approximation and the Douglas—Kroll method. The calculated dipole moments are in agreement with available experimental data. In the case of the quadrupole moment of KF, the discrepancy between the experimental and theoretical values is interpreted in favour of the theoretical result. The electron correlation contribution to electric properties of the alkali metal fluorides is relatively small. The only truly ‘relativistic’ molecule in the series is FrF. Both the electron correlation and relativistic contributions to dipole and quadrupole moments and dipole polarizabilities in this series of ionic diatoms can be qualitatively interpreted in terms of a very simple model of polarizable charges.