Systematic analysis of plasmonic resonances using GPU-enabled real-time, time-dependent DFTB

BRYAN M. WONG; NIRANJAN V. ILAWE; MARÍA BELÉN OVIEDO

Congreso; ACS National Meeting - Washington 2017; 2017

Recent advances in the study of local surface plasmon resonances (LSPRs) in metallic nanoparticles (NPs) have led to the emergence of novel applications in chemical and biological sensing, optical transmission, nanophotonic devices, and energy harvesting. Crucial to the advancement of these applications is a predictive, theoretical understanding of LSPR with regard to NP shape, size, composition, and chemical environment. For example, energy-guiding plasmonic nanoantennas composed of NP arrays depend crucially on NP shape and inter-particle distance, and predictive calculations provide a rational path for understanding and tuning these plasmonic interactions. Classical electrodynamic theories, based on solving Maxwell?s equations, which are frequently used to investigate the optical properties of metal NPs, fail to account for the atomistic details and quantum effects. On the other hand, ab-initio quantum mechanical calculations such as density functional theory (DFT), while accounting for quantum properties are computationally costly and currently limited to very small systems. To this end, we describe our use the density functional tight binding (DFTB) approach and its real-time time-dependent counterpart, RT-TDDFTB that runs on massively-parallelized GPUs, to probe the excited-state dynamics of large plasmonic nanostructures. Specifically, I will discuss the results obtained by the GPU-enhanced RT-TDDFTB calculations, applied to study (1) dependence of LSPR energy on NP shape and size (2) local electric field enhancements and (3) effect of surface oxidation on LSPR energy, of NPs of sizes varying from smaller 0.7nm (55 atoms) to significantly large 7 nm (2800 atoms) NPs. In summary, my poster will demonstrate the capability of our GPU-optimized code to efficiently and accurately investigate the real-time electron dynamics of large plasmonic systems at a quantum mechanical level.