Orbital entanglement in bond-formation processes

TL;DR

This paper uses quantum information theory to analyze electron entanglement in molecular orbitals, providing insights into bond formation and dissociation processes by assessing correlation effects.

Contribution

It extends previous work by demonstrating how orbital entanglement measures can classify and understand electron correlation effects in chemical bonding.

Findings

Entanglement measures effectively classify correlation types.

Analysis reveals detailed electron correlation during bond dissociation.

Quantum information tools offer new insights into chemical bonding processes.

Abstract

The accurate calculation of the (differential) correlation energy is central to the quantum chemical description of bond-formation and bond-dissociation processes. In order to estimate the quality of single- and multi-reference approaches for this purpose, various diagnostic tools have been developed. In this work, we elaborate on our previous observation [J. Phys. Chem. Lett. 3, 3129 (2012)] that one- and two-orbital-based entanglement measures provide quantitative means for the assessment and classification of electron correlation effects among molecular orbitals. The dissociation behavior of some prototypical diatomic molecules features all types of correlation effects relevant for chemical bonding. We demonstrate that our entanglement analysis is convenient to dissect these electron correlation effects and to provide a conceptual understanding of bond-forming and bond-breaking processes from the point of view of quantum information theory.