Emil Prodan

Quantum Description of the Plasmon Resonances of a Nanoparticle Dimer

Using time-dependent density functional theory, we present a fully quantum mechanical investigation of the plasmon resonances in a nanoparticle dimer as a function of interparticle separation. We show that for dimer separations below 1 nm quantum mechanical effects, such as electron tunneling across the dimer junction and screening, significantly modify the optical response and drastically reduce the electromagnetic field enhancements relative to classical predictions. For larger separations, the dimer plasmons are well described by classical electromagnetic theory.

Plasmon hybridization in spherical nanoparticles.

We show that the plasmon resonances in single metallic nanoshells and multiple concentric metallic shell particles can be understood in terms of interaction between the bare plasmon modes of the individual surfaces of the metallic shells. The interaction of these elementary plasmons results in hybridized plasmons whose energy can be tuned over a wide range of optical and infrared wavelengths. The approach can easily be generalized to more complex systems, such as dimers and small nanoparticle aggregates.

Quantum Plasmonics: Optical Properties and Tunability of Metallic Nanorods

The plasmon resonances in metallic nanorods are investigated using fully quantum mechanical time-dependent density functional theory. The computed optical absorption curves display well-defined longitudinal and transverse plasmon resonances whose energies depend on the aspect ratio of the rods, in excellent agreement with classical electromagnetic modeling. The field enhancements obtained from the quantum mechanical calculations, however, differ significantly from classical predictions for distances shorter than 0.5 nm from the nanoparticle surfaces. These deviations can be understood as arising from the nonlocal screening properties of the conduction electrons at the nanoparticle surface.

The effect of a dielectric core and embedding medium on the polarizability of metallic nanoshells

Using the time dependent density functional method we investigate the effects of a dielectric core and a dielectric embedding medium on the optical properties of metallic nanoshells. The polarizability is shown to be strongly influenced by the presence of the dielectric which induces additional screening charges that need to be included self-consistently. We show that the energies of the dipolar plasmon resonances depend strongly on the dielectric constant of the core or embedding medium. The results compare very well with classical Mie scattering theory calculations.

Effects of dielectric screening on the optical properties of metallic nanoshells

The time dependent density functional method for the calculation of optical properties of metallic nanoshells is extended to include the combined influence of a dielectric core and a dielectric embedding medium. The coupling between the polarization charges at the inner and outer surfaces of the shell is found to strongly influence the position of the plasmon resonances. The method is applied to gold nanoshells with gold sulfide cores in water for two different diameters, and the energies of the calculated plasmon resonances are found to be in good agreement with experimental measurements.

Robustness of the spin-Chern number

The spin Chern

Bulk and Boundary Invariants for Complex Topological Insulators: From K-Theory to Physics

({C}_{s})

Quantum plasmonics: optical properties of a nanomatryushka.

was originally introduced on finite samples by imposing spin boundary conditions at the edges. This definition leads to confusing and contradictory statements. On one hand, the original paper by Sheng et al. revealed robust properties of

Disordered topological insulators: a non-commutative geometry perspective

{C}_{s}

Electronic structure and polarizability of metallic nanoshells

against disorder and certain deformations of the model and, on the other hand, several people pointed out that