First Principles Studies on the Electronic Structure and Band Structure of Paraelectric SrTiO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; by Different Approximations

H Salehi

doi:10.4236/jmp.2011.29111

Abstract

The electronic structure, energy band structure, total density of states (DOS) and electronic density of perovskite SrTiO3 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 Γ 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 TiO2 is mainly ionic and that the TiO2 entities bond covalently.The calculated band structure and density of state of SrTiO3 are in good agreement with theoretical and experimental results.

Highlights

Ferroelectric and related materials having chemical formula ABO3 have been the subject of extensive investigation, both because of their technical importance and because of the fundamental interest in the physics of their phase transitions [1]
The electronic structure, energy band structure, total density of states (DOS) and electronic density of perovskite SrTiO3 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
From the DOS analysis, as well as charge-density studies, I have conclude that the bonding between Sr and TiO2 is mainly ionic and that the TiO2 entities bond covalently.The calculated band structure and density of state of SrTiO3 are in good agreement with theoretical and experimental results

Summary

Introduction

Ferroelectric and related materials having chemical formula ABO3 have been the subject of extensive investigation, both because of their technical importance and because of the fundamental interest in the physics of their phase transitions [1]. SrTiO3 in this class has been the subject of ongoing theoretical and experimental studies because of its unusual dielectric property which deviates from those of other ABO3 perovskites While it has the simple cubic structure at high temperature, SrTiO3 goes through an AFD transition at 105 K to a tetragonal phase in which the oxygen octahedra have rotated by a smal angle along the c-axis in opposite senses in neighbouring unit cells. The electronic structure, band structure, DOS and electronic density in cubic crystal SrTiO3 are studied using the Wien2k package [22] This employs the FP-LAPW method in the framework of the DFT with the GGA for solving the kohn-Sham equation [16,17]. In this method valence and core states origin energy have been separate, and –6 Ry energy bound separated between valence electrons and

Electronic Structure

Electronic Charge Density

Conclusions