A comprehensive theoretical investigation of the electronic states of Ca2 up to the Ca(4s2 S1)+Ca(4s5p P1) dissociation limit

Abstract

A theoretical survey of the electronic structure of Ca(2) is presented using two-electron pseudopotentials complemented by core-polarization operators on Ca atoms and multireference configuration interaction/quasidegenerate perturbation theory (MRCI/QDPT) treatment of molecular excited states. The spectroscopic constants of 70 electronic states up to 30,000 cm(-1) above the ground state are determined. This implies all Ca(2) states dissociating up to the Ca(4s(2) (1)S) + Ca(4s5p (3,1)P) dissociation limits. All spin states (singlet, triplet, and quintet) are investigated. The work emphasizes the variety of interactions implying singly valence and lowest Rydberg excited states, doubly excited states generated by atom pairs (3)P(4s4p) + (3)P(4s4p), or (3)P(4s4p) + (3)D(4s3d), 4p3d double excitations asymptotically localized on a single-atom. Zwitterionic Ca(+) + Ca(-) configurations are evidenced and shown to induce specific electronic patterns in (1)Σ(g)(+), (3)Σ(g)(+), (1)Σ(u)(+), (3)Σ(u)(+), (1)Π(g), (3)Π(g), (1)Π(u), and (3)Π(u) symmetry manifolds. They also provide insight for qualitative features (barriers) found for the lower electronic states already investigated in previous publications by other authors.

Theoretical predictions of properties of group-2 elements including element 120 and their adsorption on noble metal surfaces

“…The homonuclear dimers, M 2 , of Ca through Ra were a subject of experimental [16][17][18] and theoretical [19][20][21][22][23][24][25] studies in the past because of their weakly bound ground states at large interatomic distances. There are, to our knowledge, fewer data on MAu: only experimental [26][27][28] and theoretical 26 on CaAu, and theoretical 29 on BaAu.…”

Ion-neutral chemistry at ultralow energies: dynamics of reactive collisions between laser-cooled Ca+ ions and Rb atoms in an ion-atom hybrid trap

“…Thus, only the two valence electrons are treated explicitly, allowing for a full configuration interaction (FCI) calculation performed in the configuration space generated by the large Gaussian basis sets reported in Refs. [45,48]. The fine structure of the calcium ion and of the rubidium atom are neglected here as justified below.…”

Light-Assisted Ion-Neutral Reactive Processes in the Cold Regime: Radiative Molecule Formation versus Charge Exchange

“…Correlation between core and valence electrons is modeled via effective core polarization potentials. Therefore, a full configuration interaction (FCI) calculation is achievable in a configuration space built from a large basis set of Gaussian orbitals for the valence electrons [25,26]. The complete set of calculations will be presented elsewhere [21].…”