Partitioning of total charge in matter from geometric phases of electrons

TL;DR

This paper introduces a first-principles scheme using geometric phases of Bloch electrons to unambiguously partition charge in matter, providing insights into electron localization and bonding.

Contribution

It generalizes geometric phase concepts to develop a method for quantitatively distributing charge among atoms based on Kohn-Sham states.

Findings

Charge centers can be mapped to reveal inter-atomic and intra-atomic hybridization.

The method provides unbiased quantitative estimates of electron sharing.

Applicable to various systems with different valence electron sharing patterns.

Abstract

Based on geometric phases of Bloch electrons computed from first-principles, we propose a scheme for unambiguous partitioning of charge in matter, derivable directly from the Kohn-Sham states. Generalizing the fact that geometric phases acquired by electrons due to evolution of their crystal momentum $\vec k$ in a direction through out the Brillouin zone(BZ), provide position of their localization with net minimum spread along the corresponding direction in real space. We find that the total charge can be meaningfully distributed into charge centres simultaneously contributed by triads of electrons with their crystal momentum evolving linearly independently through each unique $\vec k$ across the BZ. The resultant map of charge centres readily renders not only the qualitative nature of inter-atomic as well as intra-atomic hybridization of electrons, but also unbiased quantitative estimates of electrons on atoms or shared between them, as demonstrated in a select variety of isolated and periodic systems with varying degree of sharing of valence electrons among atoms, including variants of multi-centered bonds.