Barium titanate ground- and excited-state properties from first-principles calculations

Abstract

We present a comprehensive theoretical investigation of paraelectric (cubic) and ferroelectric (tetragonal) BaTiO3. The atomic and electronic structure, piezoelectric tensor, Debye temperature, zone center phonon frequencies, and optical absorption are calculated for both phases from first principles. The structural and vibrational properties predicted from density functional theory are in good agreement with experiment and earlier theoretical work. The electronic structure and optical response are found to be very sensitive to quasiparticle and electron-hole attraction effects, which are accounted for by using the GW approach and by solving the Bethe-Salpeter equation, respectively. Electronic self-energy effects are found to open the band gap substantially, to 3.7 and 3.9 eV for the cubic and tetragonal phases, respectively. In contrast to earlier calculations, good agreement with the measured optical data is achieved. The ab initio thermodynamics predicts that the ferroelectric ordering will disappear at 419 K. It is shown that the phase transition is driven by the vibrational entropy of a variety of modes

Ab initio hybrid DFT calculations of BaTiO3, PbTiO3, SrZrO3 and PbZrO3 (111) surfaces

“…In the framework of the current paper calculated ABO 3 perovskite bulk band gap is the energy difference (in electron volts) between the top of the valence band and the bottom of the conduction band at the -point. As we can see from Table 2, the BaTiO 3 experimentally measured optical band gap is equal to 3.3 eV [53]. The calculated bulk band gap at thepoint for the BaTiO 3 perovskite 3.49 eV, using the B3LYP functional, is in an excellent agreement with the experimental value.…”

“…The calculated bulk band gap at thepoint for the BaTiO 3 perovskite 3.49 eV, using the B3LYP functional, is in an excellent agreement with the experimental value. It is worth to notice, that by Sanna et al [53] by means of the DFT calculated band gap for the BaTiO 3 bulk is 1.63 eV, but the DFT + GW band gap amount to 3.68 eV, namely very close to the experimental value and current B3LYP calculation result. The band gap at the -point calculated for PbTiO 3 crystal by means of the hybrid B3LYP functional 4.15 eV, is in a satisfactory agreement with the experiment (see Table 2).…”

Strain-Engineered Multiferroicity inPnmaNaMnF3Fluoroperovskite

“…The computed linear piezoelectric coefficients e 21 , e 23 , e 22 , e 16 , and e 34 at 0% strain are equal to 1.010, -0.672, 0.064, -0.108, and 0.058 C·m −2 respectively and are not far from the ones observed in BaTiO 3 [32,33]. From the quadratic fitting observed in Fig 2, we can extract that the overall non-linear contribution related to the sum of the B µjk components and we found it to be about 60% of the linear piezoelectric constants (e µj ).…”

Polarization and valley switching in monolayer group-IV monochalcogenides

“…The activation energy for reorientation of the P nma-ML puckering direction is very small (88 meV for SnS and 43 meV for GeSe). We note that GGA has been successful in predicting the small enthalpy differences (tens of meV) between different phases of ferroelectric materials, because systematic errors cancel out when comparing systems with very similar structures [32]. The broken inversion symmetry and total energy with a typical double-well potential of SnS and GeSe are the first two indications that these materials may possess ferroelectricity.…”