Low-lying energy spectrum of the cerium dimer

TL;DR

This paper investigates the low-energy electronic spectrum of the cerium dimer using a valence bond model focusing on 4f electrons, revealing how their interactions shape the energy levels and magnetic properties.

Contribution

It introduces an analytical valence bond model for Ce2 that accounts for 4f electron interactions, providing insights into the energy spectrum and magnetic behavior.

Findings

Ground state is the even 0 level with 4f states influence

Lowest excitations occur at 30 K with specific 0 states

Magnetic susceptibility varies with temperature and spin-orbit coupling

Abstract

The electronic structure of Ce2 is studied in a valence bond model with two 4f electrons localized at two cerium sites. It is shown that the low-lying energy spectrum of the simplest cerium chemical bond is determined by peculiarities of the occupied 4f states. The model allows for an analytical solution which is discussed along with the numerical analysis. The energy spectrum is a result of the interplay between the 4f valence bond exchange, the 4f Coulomb repulsion and the spin-orbit coupling. The calculated ground state is the even \Omega=\Lambda=\Sigma=0 level, the lowest excitations situated at 30 K are the odd \Omega=\Lambda=\Sigma=0 state and the $^{3} 6_5$ doublet (\Omega=\pm5,\, \Lambda=\pm6,\, \Sigma=\mp1). The calculated magnetic susceptibility displays different behavior at high and low temperatures. In the absence of the spin-orbit coupling the ground state is the ${}^3 \Sigma_g^-$ triplet. The results are compared with other many-electron calculations and experimental data.