Excited states of beryllium atom from explicitly correlated wave functions

Abstract

A study of the first excited states of beryllium atom starting from explicitly correlated wave functions is carried out. Several properties are obtained and discussed focusing on the analysis of the Hund's rules in terms of the single-particle and electron pair intracule and extracule densities. A systematic study of the differences on the electronic distributions of the singlet and triplet states is carried out. The trial wave function used to describe the different bound states consists of a generalized Jastrowtype correlation factor times a configuration interaction model wave function. This model wave function has been fixed by using a generalization of the optimized effective potential method to deal with multiconfiguration wave functions. The optimization of the wave function and the calculation of the different quantities is carried out by means of the Variational Monte Carlo method.

Beryllium in strong magnetic fields

“…For γ = 0 we have a relative accuracy of 10 −3 compared to the values presented in Ref. [42]. In the presence of the field for γ ≤ 0.5 our variational total energies are larger than those of Ref.…”

“…For the field-free case the relative accuracy is approximately 2 × 10 −3 in comparing with the highly accurate values presented in Ref. [42]. In the presence of the field for γ ≤ 0.5 the comparison with Ref.…”

“…Total energies for this state are available only for a vanishing external field and our computed value shows in this case a relative accuracy of 10 −3 compared to the value provided in Ref. [42]. Let us turn to the discussion of our results for the triplet symmetry shown in Fig.…”

“…For γ > 2 the ionization energy decreases as a function of γ at a much lower rate. Only for γ = 0 energies of this state are available for comparison [42] i.e. this state has not been investigated previously in the literature.…”

“…Total energies E Tot , one-particle ionization energies E Ion , and previously published data for the total energies E Lit in a. u. for the states ν 1 0 + (ν = 1, 2, 3), as well as the symmetry T Sym of the Be + ion belonging to the ionization threshold for different field strengths γ. a Ref. [42]. b Ref.…”