arXiv : 0704 . 2323 v 1 [ physics

The bandstructure was calculated by the full-potential linearized augmented plane wave method. The result reveals two important insights to the novel second harmonic generation (SHG) of alpha-phase lithium iodate (α− LiIO3) crystal: the existence of finite intraband momentum matrix elements due to the non-inversion symmetry of the crystal illuminating the potential of the intra-band transition, and the strong covalent bonding between the I-atoms and the ligand O-atoms resulting the condition of the double-resonance. An interband transition scenario in SHG as α− LiIO3 in nanostructure is proposed. The optical properties were calculated within the theoretical framework of the timedependent perturbation of the independent-particle model. The dielectric tensors and the refractive index were evaluated. Comparisons between the predictions and the re⋆ Present address: Computational Materials Science Center, National Institute for Materials Science, Sengen 1-21 Tsukuba, Ibaraki, Japan, 305-0047, Tel/Fax:+81-29-8588003 sults were made: the x-ray near edge absorption spectra; the refractive index at the static limit, and at finite frequencies. Possible factors attributing the calculation errors is discussed. PACS 42.70.Mp, 73.20.At, 78.20.Ci