Polarizabilities of the Mg$^+$ and Si$^{3+}$ ions

TL;DR

This paper calculates the polarizabilities of Mg$^+$ and Si$^{3+}$ ions using advanced semi-empirical and relativistic methods, refining previous estimates and providing accurate values for atomic physics applications.

Contribution

It introduces a combined semi-empirical and relativistic all-order method to accurately compute ion polarizabilities, updating previous experimental and theoretical values.

Findings

Polarizabilities of Mg$^+$ and Si$^{3+}$ are precisely determined.

The revised analysis shows significant changes in polarization plot slopes.

Calculated polarizabilities agree within 0.3% of experimental values.

Abstract

A polarization analysis of the fine-structure intervals for the $n = 17$ Rydberg states of Mg and the $n = 29$ states of Si$^{2+}$ is performed. The coefficients of all terms in the polarization expansion up to $r^{-8}$ were computed using a semi-empirical single electron analysis combined with the relativistic all-order single-double method (MBPT-SD) which includes all single-double excitations from the Dirac-Fock wave functions to all orders of perturbation theory. The revised analysis yields dipole polarizabilities of $\alpha_1 = 35.04(3)$ a.u. for Mg$^+$ and $\alpha_1 = 7.433(25)$ a.u. for Si$^{3+}$, values only marginally larger than those obtained in a previous analysis (E. L. Snow and S. R. Lundeen (2007) Phys. Rev. A {\bf 75} 062512, {\em ibid} (2008) {\bf 77} 052501). The polarizabilities are used to make estimates of the multiplet strength for the resonant transition for both ions. The revised analysis did see significant changes in the slopes of the polarization plots. The dipole polarizabilities from the MBPT-SD calculation, namely 35.05(12) a.u. and 7.419(16) a.u., are within 0.3% of the revised experimental values.