Relativistic coupled-cluster studies of dipole polarizabilities in closed-shell atoms

We investigate the role of electron correlation effects in the electric-dipole polarizabilities of the ground states of the alkaline earth metals, helium, and ytterbium by employing the relativistic coupled-cluster (RCC) theory. These effects are incorporated via the residual Coulomb interaction to all orders in the RCC singles and doubles approximations. The perturbed wave functions used in the calculations of the polarizabilities are obtained by directly solving the first-order perturbed RCC equations, thereby avoiding the sum-over-states approach. Our results are compared with other calculations and available experimental data.

Figure 1

Breakdown of the $\overline{D_z}{T}_1^{\left(1\right)}$ CC diagram in terms of lower-order MBPT and RPA diagrams that contribute significantly to the polarizability calculations. Here, $D_z$ and ${\text{V}}_N$ represent the dipole and normal-order Coulomb interaction operators which are shown as single dotted and dashed lines, respectively. The notations $c$ and $i$ represent the occupied and unoccupied orbitals, respectively, of the considered systems.