The Importance of Static Correlation in the Band Structure of High Temperature Superconductors

TL;DR

This paper highlights the critical role of static correlation effects in accurately modeling the band structure of high-temperature superconductors, demonstrating how conventional methods fail and proposing corrections that reveal a second Fermi level crossing.

Contribution

It identifies the failure of standard band structure calculations due to static correlation and introduces a correction method that predicts the second Fermi level crossing in cuprates.

Findings

Conventional methods fail to capture static correlation effects.

Corrected calculations reveal a second Fermi level crossing.

This insight explains key physical phenomena in high-temperature superconductors.

Abstract

Recently we presented a new band structure for La(2-x)Sr(x)CuO(4) and other high temperature superconductors in which a second narrow band was seen to cross the primary band at the Fermi level. The existence of this second Fermi level band is in complete disagreement with the commonly accepted LDA band structure. Yet it provided a crucial piece of physics which led to an explanation for superconductivity and other unusual phenomena in these materials. In this work we present details as to the nature of the failure of conventional methods in deriving the band structure of the cuprates. In particular, we use a number of chemical analogues to describe the problem of static correlation in the band structure calculations and show how this can be corrected with the predictable outcome of a Fermi level band crossing.