Discrete sources method for modeling the nonlocal optical response of a nonspherical particle dimer

A modified scheme of the discrete sources method for modeling the nonlocal optical response of a plasmonic dimer consisting of two identical axisymmetric metallic particles has been developed. The optical cross sections have been computed in the frequency domain for prolate spheroids with different aspect ratios and for different gap sizes. The results show that the generalized nonlocal optical response model leads to a blue shift, a plasmon mode damping, and a plasmon mode broadening of the optical cross sections as compared to the local-response approximation. These effects more pronounced when the aspect ratio of the spheroid increases and the gap size decreases. It has been confirmed that the additional boundary condition appears to be the main origin for the blue shift.