Delocalized electrons: conductivity and superconductivity

TL;DR

This paper explores the nature of electron localization and delocalization in crystals, linking these properties to conductivity and superconductivity, and extends the understanding to cuprate superconductors with ab initio insights.

Contribution

It introduces a wavefunction projection approach revealing electron duality and proposes a unified explanation for conductivity and superconductivity, including in cuprates.

Findings

s orbital electrons exhibit localization-delocalization duality

Charge carriers for conductivity are delocalized electrons

Superconductivity involves electron pairs of s wave

Abstract

When wavefunction of crystal was projected out in atomic basis, we found that electrons of s orbital had localization-delocalization duality, and the ones of p and d orbital were only localized in three dimensional crystal lattice. The existence of s type delocalized electrons is based on three dimensional ordering of electron density in metals. Then charge carriers of metals for conductivity are just such delocalized electrons so that the ones for superconductivity are electron pairs of s wave. This way could also be generalized to two dimensional case for CuO2 plane of cuprate superconductor to explain its phase diagram qualitatively. We also gave some ab initio explain for Hubbard model.