Polarizabilities of Si^{2+}: a benchmark test of theory and experiment

TL;DR

This paper presents highly precise calculations of the electric-dipole polarizabilities of Si^{2+} ion states, confirming theoretical models with experimental data and providing a benchmark for divalent atom studies.

Contribution

It introduces a highly accurate configuration interaction + all-order method for polarizability calculations and validates it against experimental results for Si^{2+}.

Findings

Calculated polarizabilities agree with experimental values within uncertainties.

Identified near cancellation of polarizabilities in ground and excited states of Si^{2+}.

Established the most precise benchmark test for theory and experiment in divalent atoms.

Abstract

We have calculated electric-dipole polarizabilities of the 3s^2 ^1S_0, 3s3p ^3P_0, and 3s3p ^1P_1 states of the Si^{2+} ion using recently developed configuration interaction + all-order method. Detailed evaluation of the uncertainties of the final results is carried out. Our value for the ground state electric-dipole polarizability 11.670(13) a.u. is in excellent agreement with the resonant excitation Stark ionization spectroscopy value 11.669(9) a.u. [Komara et al., J. Phys. B 38, 87 (2005); Mitroy, Phys. Rev. A 78, 052515 (2008)]. This work represents the most precise benchmark test to date of theory and experiment in divalent atoms. The near cancellation of the ns^2 ^1S_0 ground state and the lowest nsnp ^3P_0 polarizabilities previously observed in B+, Al+, In+, Tl+, and Pb^{2+} is also found in Si^{2+} ion.