The band structure and the optical properties of Ba0.5Sr0.5TiO3 are studied by the first principles method. The results show that the conduction band and the valence band are derived from the hybridization between titanium 3d orbitals and oxygen 2p orbitals. In the conduction band, titanium 3d orbitals play a primary role, while in the valence band, oxygen 2p orbitals play a primary role. The absorption coefficient is as targe as 105cm-1, and the absorption is mainly localised in the low energy region. The refractive index n（0） equals 2.1. Our results are in good agreement with the experimental results.

A ZnO film with two-dimensional periodic structure was grown on Si substrate by radio-frequency plasma-assisted molecular beam epitaxy. The influence of wet-chemical etching on Si (100) and Si (111) substrates patterned with dot arrays was investigated for achieving a ZnO film with good periodic structure. X-ray diffraction and scanning electron microscopy mesurements demonstrate better crystalline quality and surface morphology of ZnO film grown on Si (111) than that on Si (100). The results suggest that the growth method is feasible for the fabrication of ZnO film with good periodic structure.

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In this paper, the D→Klv～l decay is researched using by QCD light cone sum rules. Firstly, the form factor of D→K is calculated by choosing a new correlative function to eliminate the effect caused by the uncertainty of twist-3 function, so the calculation result of form factor is more precise, and the branching ratio is consistent with the experimental data.