Molecules in Environments: Towards Systematic Quantum Embedding of Electrons and Drude Oscillators

TL;DR

This paper introduces a quantum embedding method that accurately models molecule-environment interactions, including many-body correlations, using a variational approach combined with Monte Carlo techniques.

Contribution

It presents a novel quantum embedding framework that explicitly incorporates many-body effects between molecules and environments modeled by quantum oscillators.

Findings

Accurately predicts solvation energies of benzene derivatives.

Achieves excellent agreement with ab initio calculations.

Effectively models electrostatic, polarization, and dispersion interactions.

Abstract

We develop a quantum embedding method that enables accurate and efficient treatment of interactions between molecules and an environment, while explicitly including many-body correlations. The molecule is composed of classical nuclei and quantum electrons, whereas the environment is modeled via charged quantum harmonic oscillators. We construct a general Hamiltonian and introduce a variational ansatz for the correlated ground state of the fully interacting molecule/environment system. This wavefunction is optimized via variational Monte Carlo and the ground state energy is subsequently estimated through diffusion Monte Carlo. The proposed scheme allows an explicit many-body treatment of electrostatic, polarization, and dispersion interactions between the molecule and the environment. We study solvation energies and excitation energies of benzene derivatives, obtaining excellent agreement with explicit ab initio calculations and experiment.