%0 Journal Article %T First Principles Studies on the Electronic Structure and Band Structure of Paraelectric SrTiO<sub>3</sub> by Different Approximations %A H. Salehi %J Journal of Modern Physics %P 934-943 %@ 2153-120X %D 2011 %I Scientific Research Publishing %R 10.4236/jmp.2011.29111 %X The electronic structure, energy band structure, total density of states (DOS) and electronic density of perovskite SrTiO<sub>3</sub> in the cubic phase are calculated by the using full potential-linearized augmented plane wave (FP-LAPW) method in the framework density functional theory (DFT) with the generalized gradient approximation (GGA) by WIEN2k package. The calculated band structure shows a direct band gap of 2.5 eV at the ¦£ point in the Brillouin zone.The total DOS is compared with experimental x-ray photoemission spectra. From the DOS analysis, as well as charge-density studies, I have conclude that the bonding between Sr and TiO<sub>2</sub> is mainly ionic and that the TiO<sub>2</sub> entities bond covalently.The calculated band structure and density of state of SrTiO<sub>3</sub> are in good agreement with theoretical and experimental results. %K Electronic Structure %K SrTiO< %K sub> %K 3< %K /sub> %K WIEN2k %K FP-LAPW %K DFT %K GGA %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=7132