Real-Time Quantum Dynamics in Plasmonic Nanoparticle Arrays

In this talk, I will present a unique analysis of electronic couplings that mediate excitation energy transfer (EET) in plasmonic nanoparticle arrays using large-scale quantum dynamical calculations. To capture the intricate electronic interactions in these large systems, real-time, time-dependent, density functional tight binding (RT-TDDFTB)^1-3 is used to characterize the quantum-mechanical efficiency of EET in plasmonic nanoparticle chains with subnanometer interparticle spacings. In contrast to classical electrodynamics methods, our quantum dynamical calculations give qualitatively different results for EET when the interparticle spacing between the nanoparticles of the nanoantenna is decreased. Most notably, we show a sudden drop in EET efficiencies as the interparticle distance decreases, which we attribute to the onset of quantum charge tunneling between the nanoparticles.^1,2 We further characterize this abrupt change in EET efficiency through visualizations of both the spatial and time-dependent charge distributions within the nanoantenna, which provide an intuitive classification of the various types of electronic excitations in these plasmonic systems. Finally, while the use of classical electrodynamics methods has long been used to characterize complex plasmonic systems, our findings demonstrate that quantum-mechanical effects can result in qualitatively different (and sometimes completely opposite) results that are essential for accurately calculating EET mechanisms and efficiencies in these nanoparticle systems.<br/><br/><i>J. Chem. Theory Comput.</i> 2017, 13, 3442–3454<br/><i>J. Mater. Chem. C</i>, 2018, 6, 5857-5864<br/><i>J. Chem. Theory Comput</i>. 2023, 19, 7989–7997