Rigorous screened interactions for realistic correlated electron systems

TL;DR

This paper introduces a first principles method for accurately deriving static two-body interactions in correlated electron systems, improving the fidelity of low-energy Hamiltonians by conserving correlation functions and capturing long-range effects.

Contribution

It presents a rigorous algebraic approach that conserves correlation functions and enhances the description of screening and long-range interactions in quantum embedding frameworks.

Findings

Faithfully describes relaxation of local subspaces in molecular systems

Enables systematic improvement of long-range plasmonic interactions in graphene

Improves accuracy over traditional static approximations

Abstract

We derive a widely-applicable first principles approach for determining two-body, static effective interactions for low-energy Hamiltonians with quantitative accuracy. The algebraic construction rigorously conserves all instantaneous two-point correlation functions in a chosen model space at the level of the random phase approximation, improving upon the traditional uncontrolled static approximations. Applied to screened interactions within a quantum embedding framework, we demonstrate these faithfully describe the relaxation of local subspaces via downfolding high-energy physics in molecular systems, as well as enabling a systematically improvable description of the long-range plasmonic contributions in extended graphene.