QM/Classical Modeling of Surface Enhanced Raman Scattering Based on Atomistic Electromagnetic Models

We present quantum mechanics (QM)/frequency dependentfluctuatingcharge (QM/omega FQ) and fluctuating dipoles (QM/omega FQF mu)multiscale approaches to model surface-enhanced Raman scattering spectraof molecular systems adsorbed on plasmonic nanostructures. The methodsare based on a QM/classical partitioning of the system, where theplasmonic substrate is treated by means of the atomistic electromagneticmodels omega FQ and omega FQF mu, which are able to describein a unique fashion and at the same level of accuracy the plasmonicproperties of noble metal nanostructures and graphene-based materials.Such methods are based on classical physics, i.e. Drude conductiontheory, classical electrodynamics, and atomistic polarizability toaccount for interband transitions, by also including an ad-hoc phenomenologicalcorrection to describe quantum tunneling. QM/omega FQ and QM/omega FQF mu are thus applied to selected test cases, for which computed resultsare compared with available experiments, showing the robustness andreliability of both approaches.

Automated summary

We propose quantum mechanics/frequency dependent fluctuating charge (QM/ω FQ) and fluctuating dipoles (QM/ω FQFμ) multiscale approaches for modeling surface-enhanced Raman scattering spectra of molecular systems adsorbed on plasmonic nanostructures. These methods utilize classical physics to describe the plasmonic properties of noble metal nanostructures and graphene-based materials, with the inclusion of an ad-hoc correction for quantum tunneling. Selected test cases demonstrate the robustness and reliability of both QM/ω FQ and QM/ω FQFμ approaches, as their computed results agree with available experiments.