Valence calculations of lanthanide anion binding energies:6pand6sattachments to4fm(5d+6s+6p)3thresholds

Abstract

Relativistic configuration-interaction calculations have been performed for anion states representing $6p$ attachments to $4{f}^{m}5d6{s}^{2}$ states in Gd and Tb as well as $6s$ attachments to $4{f}^{m}5{d}^{2}6s$ thresholds in Pr and Gd. The $4f$ subshell was treated as corelike with the same occupancy in all correlation configurations, and recently developed methods for reducing the complexity of the $4{f}^{m}$ subgroup were also employed. Results predict a single weakly bound $(24\phantom{\rule{0.3em}{0ex}}\mathrm{meV})$ even state for ${\mathrm{Pr}}^{\ensuremath{-}}$, 12 even states and three odd states for ${\mathrm{Gd}}^{\ensuremath{-}}$ (the lowest level having an electron affinity of $234\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$), and six odd states for ${\mathrm{Tb}}^{\ensuremath{-}}$. The lowest $4{f}^{8}5d6{s}^{2}6p$ ${\mathrm{Tb}}^{\ensuremath{-}}$ state is bound relative to the neutral $4{f}^{9}6{s}^{2}$ ground state by $88\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$, indicating that the ${\mathrm{Tb}}^{\ensuremath{-}}$ ground state may actually be an attachment to the first excited state of the neutral atom. Revised calculations and analyses of the much simpler ${\mathrm{Lu}}^{\ensuremath{-}}$, ${\mathrm{La}}^{\ensuremath{-}}$, and ${\mathrm{Ce}}^{\ensuremath{-}}$ anions are also presented.