Configuration-interaction relativistic-many-body-perturbation-theory calculations of photoionization cross sections from quasicontinuum oscillator strengths

Abstract

Many applications are in need of accurate photoionization cross sections, especially in the case of complex atoms. Configuration-interaction relativistic-many-body-perturbation theory (CI-RMBPT) has been successful in predicting atomic energies, matrix elements between discrete states, and other properties, which is quite promising, but it has not been applied to photoionization problems owing to extra complications arising from continuum states. In this paper a method that will allow the conversion of discrete CI-(R)MPBT oscillator strengths (OS) to photoionization cross sections with minimal modifications of the codes is introduced and CI-RMBPT cross sections of Ne, Ar, Kr, and Xe are calculated. A consistent agreement with experiment is found. RMBPT corrections are particularly significant for Ar, Kr, and Xe and improve agreement with experimental results compared to the particle-hole CI method. The demonstrated conversion method can be applied to CI-RMBPT photoionization calculations for a large number of multivalence atoms and ions.

Nuclear-spin optical rotation in xenon

“…The interaction of excited states with the core is included in full CI-MBPT, but not in CI-hMBPT. The CI-MBPT and CI-hMBPT have been successful in noble-gas atoms and gave energies and oscillator strengths (OSs) [17][18][19], g-factors [20], photo-ionization cross-sections [21], and Verdet constants [22] in agreement with experiment. From Ne to Xe accuracy deteriorates due to increase in correlation corrections.…”