DMRG/FQ: a Polarizable Embedding Approach Combining Density Matrix Renormalization Group and Fluctuating Charges

TL;DR

This paper introduces a multiscale computational framework combining DMRG and fluctuating charges to accurately simulate excited states in solvated systems, emphasizing the role of mutual polarization.

Contribution

It presents a novel integrated DMRG/FQ method that models solvent polarization self-consistently within a multiscale quantum/classical approach for excited state calculations.

Findings

Reliable excitation energies and solvatochromic shifts obtained

Close agreement with experimental data achieved

Mutual polarization is crucial for accurate solute-solvent interactions

Abstract

We present an integrated multiscale framework that combines the Density Matrix Renormalization Group (DMRG) with a polarizable fluctuating-charge (FQ) force field for the simulation of electronic excited states in solution. The method exploits the capabilities of DMRG to accurately describe systems with strong static correlation, while the FQ model provides a self-consistent and physically grounded representation of solvent polarization within a QM/MM embedding. The DMRG/FQ approach is applied to representative solvated systems, using extensive molecular dynamics sampling. The method yields reliable excitation energies, solvatochromic shifts, and a close agreement with available experimental data. The results highlight the importance of mutual polarization for capturing specific solute-solvent interactions, particularly in systems where hydrogen bonding or directional interactions play a dominant role.