# Relativistic evaluation of the two-photon decay of the metastable 1s22s2p 3P0 state in berylliumlike ions with an effective-potential model

 Title Relativistic evaluation of the two-photon decay of the metastable 1s22s2p 3P0 state in berylliumlike ions with an effective-potential model Publication Type Journal Article Year of Publication 2016 Authors Amaro, Pedro, Fratini Filippo, Safari Laleh, Machado Jorge, Guerra Mauro, Indelicato Paul, and Santos Jose Paulo Journal Physical Review A Volume 93 Pagination 032502-8 Date Published Mar 07 Abstract The two-photon $1{s}^{2}2s2p\phantom{\rule{0.16em}{0ex}}{}^{3}{P}_{0}\ensuremath{\rightarrow}1{s}^{2}{s}^{2}\phantom{\rule{0.16em}{0ex}}{}^{1}{S}_{0}$ transition in berylliumlike ions is investigated theoretically within a fully relativistic framework and a second-order perturbation theory. We focus our analysis on how electron correlation, as well as the negative-energy spectrum, can affect the forbidden $E1M1$ decay rate. For this purpose, we include the electronic correlation via an effective local potential and within a single-configuration-state model. Due to its experimental interest, evaluations of decay rates are performed for berylliumlike xenon and uranium. We find that the negative-energy contribution can be neglected at the present level of accuracy in the evaluation of the decay rate. On the other hand, if contributions of electronic correlation are not carefully taken into account, it may change the lifetime of the metastable state by up to 20%. By performing a fully relativistic $jj$-coupling calculation, we find a decrease of the decay rate by two orders of magnitude compared to nonrelativistic $LS$-coupling calculations, for the selected heavy ions. URL http://link.aps.org/doi/10.1103/PhysRevA.93.032502 Short Title JPS_Articles