Extending Density Matrix Embedding: A Static Two-Particle Theory

TL;DR

This paper introduces EDMET, a static quantum embedding method that self-consistently incorporates two-body physics, improving the treatment of long-range interactions and screening in extended systems.

Contribution

The paper presents EDMET, a novel embedding theory that explicitly includes two-particle correlations and extends traditional methods to better handle non-local interactions.

Findings

Accurately describes phase transitions and static properties in extended Hubbard models.

Achieves good agreement with experimental optical gaps in conjugated molecules.

Provides an analytic framework for self-consistent Coulomb-exchange-correlation kernels.

Abstract

We introduce Extended Density Matrix Embedding Theory (EDMET), a static quantum embedding theory explicitly self-consistent with respect to local two-body physics. This overcomes the biggest practical and conceptual limitation of more traditional one-body embedding methods, namely the lack of screening and treatment of longer-range interactions. This algebraic zero-temperature embedding augments a local interacting cluster model with a minimal number of bosons from a description of the full system correlations via the random phase approximation, and admits an analytic approach to build a self-consistent Coulomb-exchange-correlation kernel. For extended Hubbard models with non-local interactions, this leads to the accurate description of phase transitions, static quantities and dynamics. We also move towards ab initio systems via the Parriser--Parr--Pople model of conjugated coronene derivatives, finding good agreement with experimental optical gaps.