Atomistic\nMultiscale Modeling of Colloidal Plasmonic\nNanoparticles

A novel fully atomistic multiscale classical approach\nto model\nthe optical response of solvated real-size plasmonic nanoparticles\n(NPs) is presented. The model is based on the coupling of the Frequency\nDependent Fluctuating Charges and Fluctuating Dipoles (ωFQFμ),\nspecifically designed to describe plasmonic substrates, and the polarizable\nFluctuating Charges (FQ) classical force field to model the solvating\nenvironment. The resulting ωFQFμ/FQ approach accounts\nfor the interactions between the radiation and the NP, as well as\nwith the surrounding solvent molecules, by incorporating mutual interactions\nbetween the plasmonic substrate and solvent. ωFQFμ/FQ\nis validated against reference TD-DFTB/FQ calculations, demonstrating\nremarkable accuracy, particularly in reproducing plasmon resonance\nfrequency shifts for structures below the quantum-size limit. The\nflexibility and reliability of the approach are also demonstrated\nby simulating the optical response of homogeneous and bimetallic NPs\ndissolved in pure solvents and solvent mixtures.