Polarizability of the Si2+ ion

The dipole polarizability of the Si2+ ground state has been determined by a large-scale configuration-interaction (CI) calculation using the sum-over-states approach. The CI calculation was used to describe the valence electron dynamics with respect to the Hamiltonian which treats core-valence correlations with a semiempirical approach. Various higher-order polarizabilies were computed, and this permitted a more refined analysis of the energy intervals measured by resonant excitation Stark ionization spectroscopy (RESIS). The polarizability derived from the revised analysis of the RESIS data was 11.669 (9) a.u., only 0.03% larger than that reported in Komara [J. Phys. B 38, 87 (2005)]. The CI value of the polarizability, 11.688 a.u., was only 0.2% larger than experiment, while the quadrupole polarizability of 35.75 a.u. was also consistent with experiment. A resonant oscillator strength of 1.621(3) was derived from the experimental dipole polarizability. � 2008 The American Physical Society.