ELECTRON-CORRELATION AND RELATIVISTIC CONTRIBUTIONS TO ATOMIC DIPOLE POLARIZABILITIES - ALKALI-METAL ATOMS

Electric-dipole polarizabilities of K, Rb, Cs, and Fr are calculated in the framework of the quasirelativistic method based on mass-velocity and Darwin terms in the Pauli Hamiltonian. The electron-correlation contribution due to atomic cores is taken into account at two levels of approximation. The next-to-valence-shell contributions follow from the appropriate complete active-space multiconfiguration self-consistent-field calculations while the remaining core correlation effects are evaluated by using a second-order-perturbation method. Both pure relativistic and mixed correlation-relativistic contributions are evaluated. The present nonrelativistic results for K (44.6 angstrom3), Rb (60.8 angstrom3), Cs (72.8 angstrom3 ), and Fr (81.8 angstrom3 ) are reduced by 0.8 angstrom3, 11.3 angstrom3, 11.5 angstrom3, and 33.5 angstrom3 , respectively, due to relativistic and correlation-relativistic corrections. The quasirelativistic results for K, Rb, and Cs are in good agreement with experimental data. The predicted dipole polarizability of Fr is 48.3 angstrom3. Additionally, polarized basis sets for Cs and Fr for calculations of molecular electric properties have been generated in this study.