Mixed Atomistic-Implicit Quantum/Classical Approach to Molecular Nanoplasmonics

TL;DR

This paper introduces a multiscale quantum/classical method combining atomistic and continuum models to simulate the optical properties of molecular nanoplasmonic systems, including SERS, with improved efficiency and accuracy.

Contribution

A novel integrated QM/ωFQFμ-BEM approach that models complex nanostructures combining atomistic and continuum descriptions, extended to include SERS calculations within TDDFT.

Findings

The method accurately reproduces optical properties compared to fully atomistic models.

It efficiently models large nanostructures with mixed atomistic-continuum regions.

The approach successfully computes SERS signals within a quantum framework.

Abstract

A multiscale QM/classical approach is presented, that is able to model the optical properties of complex nanostructures composed of a molecular system adsorbed on metal nanoparticles. The latter are described by a combined atomistic-continuum model, where the core is described using the implicit boundary element method (BEM) and the surface retains a fully atomistic picture and is treated employing the frequency-dependent fluctuating charge and fluctuating dipole ($\omega$FQF$\mu$) approach. The integrated QM/$\omega$FQF$\mu$-BEM model is numerically compared with state-of-the-art fully atomistic approaches, and the quality of the continuum/core partition is evaluated. The method is then extended to compute Surface-Enhanced Raman Scattering (SERS) within a Time-Dependent Density Functional Theory (TDDFT) framework.