Quasiparticle self-consistent GW study of cuprates: electronic structure, model parameters, and the two-band theory for Tc

TL;DR

This study uses the quasiparticle self-consistent GW method to analyze the electronic structure of cuprates, revealing features that support a two-band theory explaining the material dependence of high-temperature superconductivity.

Contribution

It demonstrates that QSGW provides a more accurate electronic structure of cuprates than LDA, supporting the two-band theory for Tc variation.

Findings

QSGW enlarges the energy level splitting between dx2-y2 and d3z2-r2 orbitals.

QSGW lowers the van Hove singularity point.

Results align better with experimental data than LDA.

Abstract

Despite decades of progress, an understanding of unconventional superconductivity still remains elusive. An important open question is about the material dependence of the superconducting properties. Using the quasiparticle self-consistent GW method, we re-examine the electronic structure of copper oxide high-Tc materials. We show that QSGW captures several important features, distinctive from the conventional LDA results. The energy level splitting between dx2-y2 and d3z2-r2 is significantly enlarged and the van Hove singularity point is lowered. The calculated results compare better than LDA with recent experimental results from resonant inelastic xray scattering and angle resolved photoemission experiments. This agreement with the experiments supports the previously suggested two-band theory for the material dependence of the superconducting transition temperature, Tc.