Real-time time-dependent density functional theory for nanoplasmonics : Neutral and charged nanowire dimers. – (Lorenzo Stella / LPT / Seminar). – 5/09/2024, 14H

Lorenzo Stella (Université Queen’s de Belfast)

Seminar LPT, 5/09/2024, 14H, 3R1, seminar room, 3rd floor

Abstract : 
Plasmons are electron density oscillations with respect to the ionic background. Metal and heavily doped semiconductors can support volume, surface and localised plasmon modes. In plasmonic devices, plasmonic modes are used, e.g., for chemical sensing, promoting catalysis and localised heating. Numerical modelling of plasmonic devices is routinely done by solving macroscopic Maxwell equations, given a suitable parametrisation of the material (metal and dielectric) permittivities.

At the nanoscale, numerical models based on macroscopic permittivities are no longer reliable. At this scale, time-dependent density functional theory (TDDFT) within the adiabatic local density approximation (ALDA) already provides a reliable description of the electron density oscillations, including subtle effects due to electron spill-out and tunnelling.

In this talk, I will illustrate the application of TDDFT to nanoplasmonics using a nanowire dimer as a test-case. Well-known results for the plasmon resonance evolution of neutral dimers as a function of the nanowire distance will be compared with more recent results for their charged counterparts. Our real-time TDDFT results suggest that oppositely charged nanowires form a “nanocapacitor” which can “discharge” by means of a charge-transfer current through the gap.