Time-Dependent Kohn-Sham Electron Dynamics Coupled with Nonequilibrium Plasmonic Response via Atomistic Electromagnetic Model

Computational modeling of plasmon-mediated molecular photophysical and photochemical behaviours can help us better understand and tune the bound molecular properties and reactivity, and make better decisions to design and control nanostructures. However, computational investigations of coupled plasmon-molecule systems are challenging due to the lack of accurate and efficient protocols to evaluate these systems. Here we present a hybrid scheme by combining real time time-dependent density functional theory (RT-TDDFT) method with time-domain frequency dependent fluctuating charge (TD-ωFQ) model. At first, we transform ωFQ, which was formulated in the frequency domain, to time-domain and derive its equation-of-motion formulation. The TD-ωFQ introduces the nonequilibrium plasmonic response of metal nanoparticle (MNP) and atomistic interactions to the electronic excitation of QM region. Then we combine TD-ωFQ with RT-TDDFT. The derived RT-TDDFT/TD-ωFQ scheme allows us to effectively simulate the plasmon-mediated “real-time” electronic dynamics and even the coupled electron-nuclear dynamics by combining with the nuclear dynamics approaches. As a first application of the RT-TDDFT/TD-ωFQ method, we study the nonradiative decay rate and plasmon-enhanced absorption spectra of two small molecules in the proximity of sodium MNPs. Thanks to the atomistic nature of ωFQ model, the edge effect of MNP to absorption enhancement has also been investigated. and unveiled.