Multiscale Maxwell-Schrodinger modeling: A split field finite-difference time-domain approach to molecular nanopolaritonics

We present a combined finite-difference time-domain/linear response approach for modeling plasmon/molecule systems. The self-interaction of the molecule is avoided by splitting the fields and currents into two parts: those due to the molecule and those from everything else. This approach is suitable for describing surface plasmons on metal nanostructures interacting in the near field with nearby dipolar molecules or semiconductor nanostructures. The approach is applied to three collinear 5 nm diameter gold nanoparticles; the results demonstrate that a nearby molecule strongly affects surface plasmon transfer along the array. Specifically, an xy oriented molecule situated midway between the second and third nanoparticles exhibits a symmetric Fano-type inference effect. Transmission of incident x-polarized energy from the second nanoparticle to the third is enhanced over a frequency range below the molecular resonance, and partially scattered into y-polarized currents for frequencies above. At the molecule's resonance frequency, the magnitude of the resulting y-current is approximately 20% of the x-current.