Overwhelming Analogies between Plasmon Hybridization Theory and Molecular Orbital Theory Revealed: The Story of Plasmonic Heterodimers

Abstract

Plasmon hybridization theory (PHT), an analogue of molecular orbital theory (MOT) for plasmonic molecules, has enjoyed tremendous success over the last decade in discerning the optical features of hybrid nanostructures in terms of their constituent monomeric nanostructures. Dimers of metal nanoparticles served as prototypes in elucidating many of the key aspects of plasmon hybridization. Employing quantum two-state model, in conjunction with the quasi-static approximation and the finite-difference time-domain simulations, we demonstrate that the analogy between PHT and MOT can be further propelled by a theoretical estimation of the plasmon-coupling strengths and the relative contributions of the unhybridized monomeric states toward the hybrid dimeric states in plasmonic Ag–Au nanorod heterodimers. The aspect ratio of the constituent nanorods and the gap size between the monomeric nanorods can further be used as handles to tune the relative contributions of (i) the bonding and the antibonding modes to the ...