Quantum-Information Measure of Electron Localization

TL;DR

This paper introduces a new, fully non-empirical quantum information-based measure for electron localization that captures various chemical bonding phenomena and improves upon the empirical ELF.

Contribution

It presents a novel, quantum information theory-derived electron localization measure that eliminates empirical assumptions inherent in the traditional ELF.

Findings

Captures atomic shells, bonds, lone pairs, and charge transfer processes

Is straightforward to evaluate numerically

Removes ad hoc steps from the ELF formulation

Abstract

Understanding electron localization in molecules and materials plays a central role in electronic structure theory, and will increase in importance with the rise of data driven approaches. The electron localization function (ELF) is widely used to visualize electron organization in molecules and materials, and it remains a central ingredient in modern density functional approximations. Yet its formulation retains highly empirical elements. Here we introduce a fully non empirical measure of electron localization derived from the concurrence of a correlated two spin mixed state. This construction yields a genuine two point localization indicator grounded in quantum information theory, removing the ad hoc steps underlying the ELF. We show that atomic shells, covalent and ionic bonds, lone pairs, molecular dissociation, and charge transfer processes are captured. The method is straightforward to evaluate numerically.