Second Quantization Approach to Many-Body Dispersion Interactions

TL;DR

This paper introduces a second-quantized formalism for many-body dispersion interactions, enabling advanced analysis of correlations and scalable modeling of large molecular systems with quantum insights.

Contribution

The novel second-quantized MBD formalism (SQ-MBD) offers new tools for projecting observables, analyzing correlations, and applying to large-scale molecular complexes.

Findings

Provides a quantum-information framework for fragment analysis

Enables modeling of systems with millions of atoms

Offers insights into quantum fluctuations in molecules

Abstract

The many-body dispersion (MBD) framework is a successful approach for modeling the long-range electronic correlation energy and optical response of systems with thousands of atoms. Inspired by field theory, here we develop a second-quantized MBD formalism (SQ-MBD) that recasts a system of atomic quantum Drude oscillators in a Fock-space representation. SQ-MBD provides (I) tools for projecting observables (interaction energy, transition multipoles, polarizability tensors) on coarse-grained representations of the atomistic system ranging from single atoms to large structural motifs, (ii) a quantum-information framework to analyze correlations and (non)separability among fragments in a given molecular complex, and (iii) a path toward the applicability of the MBD framework to molecular complexes with millions of atoms. The SQ-MBD approach offers novel insights into quantum fluctuations in molecular systems and enables direct coupling of collective plasmon-like MBD degrees of freedom with arbitrary environments, providing a tractable computational framework to treat dispersion interactions and polarization response in intricate systems.