Electric Dipole Polarizability Of Group-13 Ions Using Perturbed Relativistic Coupled-Cluster Theory: Importance Of Nonlinear Terms

We compute the ground-state electric dipole polarizability a of the group-13 ions using the perturbed relativistic coupled-cluster theory. To account for the relativistic effects and quantum electrodynamical corrections, we use the Dirac-Coulomb-Breit Hamiltonian with the corrections from the Uehling potential and the self-energy. The effects of triple excitations are considered perturbatively in the theory. Our results for polarizability are in good agreement with previous theoretical results for all the ions. From our results we find that the nonlinear terms in perturbed relativistic coupled-cluster theory have significant contributions and must be included to obtain accurate value of dipole polarizability for group-13 ions. For the correction from the Breit interaction, we find that it is largest for Al+ and decreases with increasing Z. The corrections from the vacuum polarization and the self-energy increases with increasing Z.