Applicability of Anderson and Hubbard model for Ce metal and cerium heavy fermion compounds

TL;DR

This paper evaluates the applicability of Anderson and Hubbard models to cerium metal and heavy fermion compounds, highlighting when each model is appropriate based on inter-site $f-f$ hybridization strength.

Contribution

It demonstrates that for heavy-fermion systems like CeCu$_2$Si$_2$, the Anderson model suffices, while for cerium metal, a combined Hubbard-Anderson approach is necessary.

Findings

Anderson model is justified for CeCu$_2$Si$_2$.

Strong $f-f$ hybridization in cerium metal requires a combined Hamiltonian.

Inter-site $f-f$ hybridization varies significantly between systems.

Abstract

The importance of taking into account inter-site $f-f$ hybridization in electron structure calculations for Ce metal and cerium heavy fermion compounds was studied. We demonstrate that for heavy-fermion systems such as cerium compound CeCu$_2$Si$_2$ $f-f$ hybridization can be neglected and Anderson model application is well justified. On another hand for cerium metal $f-f$ hybridization is strong enough to provide the contribution to hybridization function comparable to hybridization between $4f$ and itinerant electrons. We argue that in the case of Ce only the most general Hamiltonian combining Hubbard and Anderson models should be used.