Plasmonic Excitations In The Nanostructures Of Tight-binding Model

Duing to the particularly characteristics in Plasmonic excitations of thenanostructures, it has been widely used in the nanophotonics and nanotechnology,which have potencial applicationes, important values, and become one of the hottopics recently. Hence, we focose our study object to one-dimensional atomic chain inthe nanostructures. Plasmonic excitations in atomic chains of nanostructure areinvestigated by employing tight-binding model. The main research is as fowllows:(1) Based on the quantum response theory, a plasma oscillation eigenfrequencies equation is derived to calculate the plasmon energy spectrum. Theplasmon energy spectrum has been numerically calculated, and providing an efficetivemethod for systematic research, which related to Plasmon excitations.(2) In the case of the intrinsic oscillations: the plasmonic excitation energy isgreater than the single-particle excitation state of same level. They are the same sizeeffect with variation of the system scale; the length of atomic chains, the electrondensity and the strength of Coulomb correlation have significant effects on theplasmon spectroscopy. In the case that the electron density of atomic chain or thenumber of electrons is not changed.The excitation energy of plasma decreases withthe atomic chain length increasing, however, the longer chains can excite morePlasmonic excitations; The excitation energy of plasma increas with the Coulombinteraction increasing; for the given atom-chain length, with variation of number ofelectrons, the excitation energy of plasma varies symmetrically around the half-filling.It indicates that the plasmon in the system is symmetrical for the electrons and holes.And the first excitation energy enlarged along with the increse of electron densitybefore electron density reaching the half-filling.(3) In the case of resonance behavior in the external electric field：We find thatthe peal value of dipole moment is corresponding to the first excited state of theplasma, and the results indicate that both the external electric field and the plasmonexcitations cause the resonance. Under the resonant frequency of the system, theoscillation amplitude of the charge is much larger than that in the case of non-resonance,When the resonant frequency of plasma and the frequency of electricfield are agreement, dipole moment and the absolute value of the charge of systemwill resonate.especially in imaginary part more obvious.