Multiscale Simulation of Quantum Nanosystems: Plasmonics of Silver Particles

TL;DR

This paper introduces a multiscale simulation method for quantum nanosystems, combining coarse-grained wave equations and short-scale equations to efficiently model complex quantum dynamics, validated against experimental and TDDFT data.

Contribution

The paper develops a novel multiscale simulation framework for quantum nanosystems that integrates long- and short-scale equations without needing experimental calibration.

Findings

Validated against experimental data and TDDFT predictions.

Successfully simulated size-dependent plasmon spectra of silver nanoparticles.

Demonstrated efficiency of the multiscale algorithm for large electron systems.

Abstract

Quantum nanosystems involve the coupled dynamics of fermions or bosons across multiple scales in space and time. Examples include quantum dots, superconducting or magnetic nanoparticles, molecular wires, and graphene nanoribbons. The number (10^3 to 10^9) of electrons in assemblies of interest here presents a challenge for traditional quantum computations. However, results from deductive multiscale analysis yield coarse-grained wave equation that capture the longer-scale quantum dynamics of these systems; a companion short-scale equation is also developed that allows for the construction of effective masses and interactions involved in the coarse-grained wave equation. The theory suggest an efficient algorithm for simulating quantum nanosystem which is implemented here. A variational Monte Carlo method is used to simulate the co-evolution of long- and short-scale processes. The approach does not require experimental data for calibration. It is validated via experimental data and TDDFT predictions on the nanoparticle size dependence of the plasmon spectrum.