Calculation of ground- and excited-state potential energy curves for barium-rare gas complexes in a pseudopotential approach

Abstract

Adiabatic potential curves for the ground state and several low-lying excited states of the barium atom interacting with Ne, Ar, Kr and Xe have been obtained from valence ab initio con®guration-interaction calculations. Atomic cores are replaced by scalar-relativistic l-dependent pseudopotentials, while core-polarization potentials are used for describing correlation contributions of the rare-gas atoms and the Ba 2 cores. Implications of the resulting potential curves for the interpretation of experimental data are discussed, together with ®rst applications of the curves for calculating absorption pro®les of the 6s 2 1 S 3 6p 1 P Ba transition.

Dynamics of highly excited barium atoms deposited on large argon clusters. I. General trends

“…They reflect the main categories of curves encountered in the full calculation. For the lowest states, the present results are in agreement with the previous calculation of Czuchaj et al 39 The ground state potential appears in Fig. 8 ͑bottom panel͒.…”

“…The calculations were performed using the CIPSI package. 41,42 The method used to calculate the Ba-Ar potential energy curves is similar to that used in our previous work on the Ca-Ar system 43 and also in investigations of other authors 39 dealing with excited states of BaAr up to 6s6p 1 P. The electronic problem is reduced to two valence electrons moving in the electric field created by two polarizable cores, Ba 2+ and Ar. An effective core potential ͑ECP͒ describes the interaction of a single electron with Ba 2+ .…”

“…Hence, Ba-Ar potential energy curves up to this energy will be considered in the discussion. A work by Czuchaj et al 39 documents the Ba-Ar system, but only low lying molecular states up to the Ba͑6s6p 1 P͒ +Ar dissociation limit ͑2.24 eV͒. Here, a calculation of the Ba-Ar molecular states, up to those correlating with Ba͑6s9p 1 P͒ + Ar, was performed, together with that of the six lowest molecular states of Ba + ͑6s ,5d͒ + Ar.…”

Observation of a barium xenon exciplex within a large argon cluster

“…21 do not suggest the existence of redshifts in the fluorescence emission as large as those reported in the present experiment. It corresponds to the excited 6p orbital aligned parallel to the cluster surface, i.e., a ⌸-like alignment with respect to the barium-argon cluster axis.…”

“…It corresponds to the excited 6p orbital aligned parallel to the cluster surface, i.e., a ⌸-like alignment with respect to the barium-argon cluster axis. 21 ͑see Table I͒, whereas a qualitative difference is reported for Hg-Xe ͑1417 cm −1 and 0.325 nm in A 1 ⌸ versus 245 cm −1 and 0.425 nm in X 1 ⌺͒. It would be very uncertain to establish a correspondence between these alignments of the 6p orbital and the peak structure of contributions C 2 and C 3 , especially because the relative arrangement of barium and xenon within the argon environment can be very diverse and continuously changing.…”