Excited S-symmetry states of positronic lithium and beryllium

Abstract

The possibility of the existence of excited S-symmetry states of positronic lithium and beryllium, resulting from the positron attachment to high-spin P parent atomic states, is examined and confirmed with variational calculations in the basis of explicitly correlated Gaussian functions. The unexpectedly different order of the energies of the S and P states is explained by the formation of the positronium cluster structure and associated disappearance of the destabilizing centrifugal force. The annihilation properties of newly discovered states are discussed in the context of prospective experimental detection.

S-wave resonances of positronic helium: all-electron study with the stabilization method

“…have similar energy and structure. Such resonances have also been hypothesized by the author for other positronic atoms which have metastable high-spin states [50].…”

“…First of all, however, no resonance has been localized below the energy of the Ps ground state formation threshold at −2.25 E h , so the hypothesis raised in the work on e + Li and e + Be [50] has not been confirmed. Moreover, the lowest energy resonances identified are the same as those which have been reported by Kar [42] and Ren [43] below the Ps(n=2) formation threshold.…”

Coupled Cluster and Quantum Monte-Carlo potential energy curves of the ground state of Be 2 and Be 2 + molecules

“…c E(Be 2 ) and E(Be 2 + ) are obtained from Refs. [64] and [31] respectively. d E(Be 2 ) and E(Be 2 + ) are obtained from Ref.…”

Bound and resonance states of positronic copper atoms

“…Although the existence of true bound states of positronic atoms is limited to some systems, their resonance states are expected to exist for a number of positronic atoms. Recent theoretical studies have performed calculations for formation, resonance and collision process of positronic atoms [24][25][26][27][28][29][30][31][32].…”