We examined the properties of photonic crystals that consist of nonoverlapping chiral spheres in a dielectric medium. We considered the effect of the chiral property of the spheres on the frequency band structure of the electromagnetic field in the crystal and on the transmittance properties of a slab of the crystal, and we estimated the optical activity of the crystal.

We present a systematic examination of the optical properties of photonic crystals consisting of metallic particles (plasma spheres) arranged periodically in a host dielectric medium. We calculate exactly the transmission and absorption coefficients of light incident on a slab of the material as functions of the frequency of the incident light and analyze the results by reference to the properties of a single sphere and to the frequency band structure of the corresponding infinite crystal. We examine the dependence of the above coefficients on the fractional volume occupied by the spheres and on the thickness of the slab. Finally we compare our results with those of the Maxwell Garnett effective-medium theory and in this way we establish the limitations of the latter. We show in particular that multipole interactions which the Maxwell Garnett theory does not take into account lead to significant structure in the transmission/absorption spectra.

We show ab initio calculations for vacancy formation energies in Cu and Al. The calculations are based on density-functional theory and the full-potential Korringa–Kohn–Rostoker Green's function method for impurities. The non-local effect beyond the local-spin-density approximation (LSDA) for density-functional theory is taken into account within the generalized-gradient approximation (GGA) of Perdew and Wang. The lattice relaxation around a vacancy is also investigated using calculated Hellmann–Feynman forces exerted on atoms in the vicinity of a vacancy. We show that the GGA calculations reproduce very well the experimental values of vacancy formation energies and bulk properties of Cu and Al, as they correct the deficiency of LSDA results (underestimation of equilibrium lattice parameters, overestimation of bulk moduli, and vacancy formation energies). It is also shown that the GGA calculations reduce the LSDA results for the lattice relaxation energy for a vacancy in Cu.