Intershell nl4f electron correlation effects

Abstract

The pair correlation energies for some n14f pairs of the ground state of the Yb atom are calculated for the first time. The partial wave (PW) increments to the second-order pair energies are generated using numerical first-order radial pair functions obtained as the solution of two-dimensional differential equations. The analysis of the PWS contributions shows the dominant role of the df, fg, and gh PWS for the 4d4f pair, of the pf and dg PWS for the 4p4f and 5p4f pairs, and of the sf and p g PWS for the 4s4f, 5s4f, and 6s4f pairs. A discussion of the similarities and differences of the structure of the correlation energy found in this paper with those calculated earlier for smaller atoms is given.

Computation of second-order correlation energies using a finite element method for atoms with d electrons

“…finally, we would like to recall that other attempts have been made to develop altemative ways to tackle the basis set problem in atomic correlation computations. To our knowledge the most important are the numerical integration methods to solve the radial pair equations [20,21], the use of numerical orbitals [22,23], the so-called 'spline method [24-321, and a numerical multiconfigurational H F method which uses a Lagrangian FEM, that has been recently developed by Sundholm and co-workers and applied to light elements (B, Li, Be, S) [33-371.…”

Accurate second‐order correlation energies for Mg and Ar

“…Some alternatives to these methods have been developed, such as numerical integration of the radial pair equations [19,20] and use of numerical orbitals [21,22], which have been employed to study some correlation effects of heavy elements and to a full extent in light elements.…”