Effective three particle forces in polyvalent atoms

TL;DR

This paper investigates how core polarization induces significant three-electron interactions in polyvalent atoms, especially with partially filled f-shells, impacting energy level calculations and requiring their inclusion for accuracy.

Contribution

It provides a detailed analysis of the conditions under which three-particle interactions become significant in polyvalent atoms, highlighting their importance in high-precision atomic calculations.

Findings

Three-particle interactions are enhanced with strong valence-core overlap.

In certain cases, these interactions significantly alter energy level ordering.

Including three-particle forces improves the accuracy of atomic energy predictions.

Abstract

We study effective three-particle interactions between valence electrons, which are induced by the core polarization. Such interactions are enhanced when valence orbitals have strong overlap with the outermost core shell, in particular for the systems with partially filled f-shell. We find that in certain cases the three-particle contributions are large, affecting the order of energy levels, and need to be included in high-precision calculations.