Many-Body Calculations of the Electron Affinity for Ca and Sr

Abstract

We have combined the quasiparticle method in many-body perturbation theory with methods used when solving the coupled-cluster equations in order to evaluate the proper self-energy potential beyond second order in perturbation theory. The method is used to calculate the affinities of Ca and Sr including second-order relativistic effects. The result is 19 meV for Ca 2 4p 1͞2 and 54 meV for Sr 2 5p 1͞2 , which are in fair agreement with experiment. [S0031-9007(96)00040-3]

The electron affinity of tellurium

“…Most prominently the binding energy of the outermost electron is substantially lower than in iso-electronic atoms due to the more efficient screening of the nuclear charge by the other electrons [3]. This increases the significance of correlation effects for the outermost electrons and makes negative ions a critical testing ground for atomic theory [4,5].…”

Near-threshold photodetachment cross section of negative atomic boron ions

“…Especially for the B (2s 2 3s 2 S) state, the energy level fits the experimental one very well after considering the core-valence electron correlation effects, suggesting that the B (2s 2 3s 2 S) state has a strong configuration interaction with the B (2s 2 4s 2 S) state. In contrast to the cases of alkaline-earth-metal atoms [19,20] whose core-valence correlations reduce the EA considerably, the effects of the core electron excitations are to increase the EA of the negative boron ions.…”

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

“…The total energy of the Be 2 for the latter method is only available in the paper and is represented in the [42]. The CAS (4,8), CAS (4,16) and CI computations with the cc-pVQZ basis set have been used (QZ abbreviation was used in the paper) for constructing the TWF. In the paper, the basis set is used in two different versions, at the first version f and g functions and at the second version only the g function are omitted.…”

“…In addition, experimental and traditional theoretical studies are not fully compatible. The isolated beryllium atom has a closed-shell electronic structure (1s 2 2s 2 ) and all of the 2p orbitals are empty and have very close energy to the occupied 2s orbital [16]. Because of this near degeneracy and existing two electrons in the valence shell, the Be could form sp hybridized bonds (such as BeH 2 ).…”