Role of the d-f Coulomb interaction in intermediate valence and Kondo systems: a numerical renormalization group study

TL;DR

This study uses numerical renormalization group methods to explore how the d-f Coulomb interaction influences magnetic susceptibility and specific heat in the Anderson model, revealing significant effects on specific heat behavior.

Contribution

It introduces the inclusion of d-f Coulomb interaction into the Anderson model and analyzes its impact on thermodynamic properties using NRG, providing new insights into intermediate valence and Kondo systems.

Findings

d-f Coulomb interaction significantly alters specific heat dependence

Magnetic susceptibility remains universal despite interactions

Renormalization of hybridization and f-level position matches Hartree-Fock results

Abstract

Using numerical renormalization group method the temperature dependences of the magnetic susceptibility $\chi(T)$ and specific heat $C(T)$ are obtained in the single-impurity Anderson model with inclusion of the $d-f$ Coulomb interaction. It is shown that the exciton effects owing to this interaction can change considerably the dependence $C(T)$ in comparison with the standard Anderson model at not too low temperatures, whereas the dependence $\chi (T)$ remains universal. The renormalization of the effective hybridization parameter and $f$-level position, which is connected with the $d-f$ interaction, is calculated, a satisfactory agreement with the Hartree-Fock approximation being derived.