Compressibility of electron gas in presence of Anderson's impurity

TL;DR

This paper uses the Anderson impurity model to analyze electron gas compressibility, revealing a large energy level separation and a decrease in compressibility near the symmetric limit.

Contribution

It applies Wiegmann's solution to compute electron gas compressibility and uncovers a novel large energy level separation affecting the Fermi energy.

Findings

Presence of a pair of neighbor levels separated by anomalously large energy

Compressibility decreases near the symmetric limit

Fermi energy crosses a pseudogap

Abstract

We employ Wiegmann's solution of the Anderson impurity model in order to compute the compressibility of electron gas. We have found that there is a pair of neighbor levels separated by anomalously large energy $\propto L^{-1/3}$, where $L$ is the size of the system. The Fermi energy crosses this pseudogap and the compressibility decreases near the so-called ``symmetric'' limit.