Three-body non-additive forces between spin-polarized alkali atoms

TL;DR

This study investigates three-body non-additive forces in spin-polarized alkali atom systems using ab initio calculations, revealing significant effects on potential well depth and equilibrium distances, mainly due to chemical bonding effects.

Contribution

It provides detailed high-level ab initio analysis of non-additive forces in alkali atom trimers, highlighting their magnitude and origin, which was previously less understood.

Findings

Non-additive forces are large near equilateral geometries.

For Li, these forces quadruple the potential well depth.

Non-additive forces reduce equilibrium interatomic distances by 0.9 Å.

Abstract

Three-body non-additive forces in systems of three spin-polarized alkali atoms (Li, Na, K, Rb and Cs) are investigated using high-level ab initio calculations. The non-additive forces are found to be large, especially near the equilateral equilibrium geometries. For Li, they increase the three-atom potential well depth by a factor of 4 and reduce the equilibrium interatomic distance by 0.9 A. The non-additive forces originate principally from chemical bonding arising from sp mixing effects.