From many-body ab initio to effective excitonic models: a versatile mapping approach including environmental embedding effects

TL;DR

This paper introduces a novel multi-state diabatization scheme based on Green's functions that effectively maps many-body ab initio calculations onto excitonic models, incorporating environmental effects for better accuracy and transferability.

Contribution

It presents a new diabatization method that combines Green's functions with environmental embedding, enabling systematic and accurate excitonic modeling from ab initio data.

Findings

Accurately describes Frenkel and charge-transfer excitons

Incorporates environmental effects via QM/MM framework

Demonstrates robustness and transferability in examples

Abstract

We present an original multi-state projective diabatization scheme based on the Green's function formalism that allows the systematic mapping of many-body ab initio calculations onto effective excitonic models. This method inherits the ability of the Bethe-Salpeter equation to describe Frenkel molecular excitons and intermolecular charge-transfer states equally well, as well as the possibility for an effective description of environmental effects in a QM/MM framework. The latter is found to be a crucial element in order to obtain accurate model parameters for condensed phases and to ensure their transferability to excitonic models for extended systems. The method is presented through a series of examples illustrating its quality, robustness, and internal consistency.