Application of time-dependent density-functional theory to the dielectric function of various nonmetallic crystals

The dielectric function of a range of nonmetallic crystals of various lattice types is studied by means of a real-space and full-potential time-dependent density-functional method within the adiabatic local-density approximation. Results for the dielectric constant e ‘ ~at optical frequencies! are given for crystals in the sodium chloride, the fluoride, the wurtzite, the diamond, and the zinc-blende lattice structure. The frequency-dependent dielectric function e(v) for the crystals in the diamond and zinc-blende lattice structure are also presented. We compare our calculated results with experimental data and other theoretical investigations. Our results for the dielectric constants e ‘ and the dielectric functions e(v) are in good agreement with the experimental values. The accuracy of the results is comparable to the one which is commonly found for time-dependent densityfunctional theory calculations on molecular systems. On average we find a deviation of 4‐5 % from experiment for the group IV and III-V compounds in the wurtzite, zinc-blende and diamond lattice structure, 8‐9 % for the II-VI and I-VII compounds in the zinc-blende and sodium chloride lattice structure, and up to 14% deviation for the fluoride lattice structure. The spectral features of the dielectric functions e(v) appear in the