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

The electronic structure and optical properties of metallic nanoshells are calculated using a jellium model and the local density approximation. An efficient implementation of the local density method enables applications to nanoshells with a very large number of conduction electrons. The frequency dependent polarizabilities of nanoshells are calculated using the time-dependent local density formalism. The optical response of these systems is characterized

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

We consider a model in which an electric field induces quantum nucleations of kink-antikink pairs in a pinned charge of spin density wave. Pair nucleation events, prevented by Coulomb blockade below a pair creation threshold, become correlated in time above threshold. The model provides a natural explanation for the observed i) small density wave polarization below threshold in NbSe3, ii) narrow band noise, iii) coherent oscillations and iv) mode-locking

An efficient method for the calculation of the electronic structure of metallic nanoshells is developed. The method is applied to a large nanoshell (of 10 nm in diameter) containing more than 25000 conduction electrons. The calculations show that the density of states of the nanoshell is relatively bulk-like. The frequency dependent polarizability is calculated and shown to display strong confinement effects and features similar to what is predicted

A method for the calculation of the electronic structure of metallic nanoshells is presented. Using this method, we investigate the role of many-electron effects in small nanoshells. A comparison of the electronic properties calculated using Hartree, Hartree-Fock and local density approximations reals that the Hartree-Fock approximation leads to unphysical results in the same way as it does for bulk electrons in metallic phases. These anomalies disappear

The dielectric permitivity of suspensions of arbitrarily shaped, shelled and charged particles is calculated in the limit of small concentrations and weak applied electrical fields. It is proved that the dielectric behaviour at low frequencies is dominated by the effects of the diffusion of the free charges on the shell surfaces. Our theoretical formula is valid in the low range of frequencies (alpha dispersion) as well as in the high range of frequencies

The problem of spontaneous pair creation in static external fields is reconsidered. A weak version of the conjecture proposed by G. Nenciu is stated and proved.

We apply the tree expansion to the polynomial self-interacting quantum fields in two dimension. In the range of small coupling constants, we show that the expansion is also convergent when the full propagator is considered and the theory is regularized by normal ordering. Explicit estimates of the convergency ranges are given.

We apply Nelson's technique of constructing Euclidean fields to the case of classical scalar fields on curved spaces. It is shown how to construct a transfer matrix and, for a class of metrics, the basic spectral properties of its generator are investigated. An application concerning the decoupling of two non-convex disjoint regions is given.