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

The major electric properties in the series of the alkali metal fluorides a re calculated with the purpose of investigating the electron correlation an d relativistic contributions. The reported results for KF, RbF, CsF, and Fr F correspond to three different levels of approximation concerning the trea tment of the electron correlation contribution to the investigated properti es. The relativistic effects are studied by using the scalar Pauli approxim ation and the Douglas-Kroll method. The calculated dipole moments are in ag reement with available experimental data. In the case of the quadrupole mom ent of KF, the discrepancy between the experimental and theoretical values is interpreted in favour of the theoretical result. The electron correlatio n contribution to electric properties of the alkali metal fluorides is rela tively 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 diat oms can be qualitatively interpreted in terms of a very simple model of pol arizable charges.