Calculations for antiferrodistortive phase of SrTiO₃perovskite: hybrid density functional study

Abstract

The electronic and atomic structure of SrTiO 3 crystals below the antiferrodistortive phase transition observed at 105 K is calculated using the hybrid B3PW functional as implemented in the ab initio CRYSTAL-2003 computer code. Such a combination of non-local exchange and correlation permits the calculation for the first time of the TiO 6 octahedron rotational angle and the ratio c/a of tetragonal lattice constants in excellent agreement with experimental data. The level splitting of the bottom of the conduction band is found to be very small, <1 meV. The predicted phase-transition induced change of the optical gap from indirect to direct is confirmed by experimental photoconductivity data.

Modeling of the cubic and antiferrodistortive phases of SrTiO3with screened hybrid density functional theory

“…For example, 10 nm of STO deposited on LaAlO 3 (LAO) undergoes a transition to the AFD phase at T c ∼ = 332 K. As the simplest metal oxide perovskite, STO has been extensively studied in the last decades with different ab initio schemes. [20][21][22][23] However, it is still a challenging material for theory; only a few of the previously published works have been able to accurately describe the structural and electronic properties of the both phases of STO. The balance of this section will consist of a brief review of the theoretical work performed to date.…”

First principle electronic, structural, elastic, and optical properties of strontium titanate

“…3,4 Many new concepts of modern condensed matter and the physics of phase transitions have been developed while investigating this unique material. [5][6][7] SrTiO 3 has applications in the fields of ferroelectricity, optoelectronics and macroelectronics. It is used as a substrate for the epitaxial growth of high temperature superconductors.…”

“…17,19,20 Theoretical calculations using several techniques have led to band gaps of SrTiO 3 in the ranges 1.71 to 2.2 eV for LDA and GGA, 6, 10, 12 1.87 to 3.63 eV for Hybrid DFT, 5,9,10 and value as high as 11.97 eV for the Hatree-Fock (HF) method. 10 In this paper, we present a simple, yet robust, and ab-initio method, based on self consistent solutions of the pertinent system of equations, [51][52][53][54] that correctly predicts band gap values and related electronic properties of SrTiO 3 rigorously, from first principle, within the LCAO-GGA formalism.…”

Phonon calculations in cubic and tetragonal phases of SrTiO3: A comparative LCAO and plane-wave study

“…However, the AFD phase geometry obtained in this study is quite far from experiment. In fact, there is the only hybrid B3PW LCAO study [13] where the correct geometry of the STO AFD phase and its energetic preference with respect to the cubic phase was predicted. It was shown therein that the doubling of the unit cell, despite tiny tetragonal distortion, changes the indirect band gap to direct one, which is well observed in photoelectron spectra.…”