title: Excited states of positronic lithium and beryllium.
abstract: Using a variational method with an explicitly correlated Gaussian basis, we study the e(+)-Li and e(+)-Be complexes in the ground and lowest excited states with higher spin multiplicity. Our calculations provide rigorous theoretical confirmation that a positron can be attached to the excited states: 1s2s2p 4P(o) and 1s²2s2p 3P(o) for e(+)-Li and e(+)-Be, respectively. The result is particularly notable for the e(+)-Be complex, as the excited 3P(o) state lies below the autoionization threshold. We report accurate binding energies, annihilation rates and structural properties of these positron-atom systems. The existence of the ground and metastable excited states with bound positron opens up a new route to the presently lacking experimental verification of stability of a positron binding to any neutral atom.
authors.affiliation: Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Sergiy
authors.initials: S
authors.lastname: Bubin
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Prezhdo