Ab Initio Computations of O and AO as well as ReO2, WO2 and BO2-Terminated ReO3, WO3, BaTiO3, SrTiO3 and BaZrO3 (001) Surfaces (original) (raw)
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Integrated Ferroelectrics, 2019
We carried out ab initio calculations for technologically important ABO 3 perovskites, like, CaZrO 3 , BaZrO 3 , PbTiO 3 and SrTiO 3 , their (001), (011) and (111) surfaces as well as (001) interfaces. For ABO 3 perovskites, such as CaZrO 3 , BaZrO 3 , PbTiO 3 and SrTiO 3 , in most of cases, all upper (001) surface layer atoms relax inwards, all second surface layer atoms relax outwards, and again, all third surface layer atoms relax inwards. Our calculated CaZrO 3 , BaZrO 3 , PbTiO 3 and SrTiO 3 (001) surface energies are almost equivalent for both AO and BO 2-terminations, and always considerably smaller than the (011) and especially (111) surface energies. Our calculated BaTiO 3 /SrTiO 3 , SrZrO 3 /PbZrO 3 and PbTiO 3 /SrTiO 3 (001) heterostructure band gap depends much more strongly from the termination of the upper augmented layer (AO or BO 2) than from the number on the substrate augmented layers.
Comparative Ab Initio Calculations of ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) Surfaces
Crystals, 2020
We performed, for first time, ab initio calculations for the ReO2-terminated ReO3 (001) surface and analyzed systematic trends in the ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surfaces using first-principles calculations. According to the ab initio calculation results, all ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surface upper-layer atoms relax inwards towards the crystal bulk, all second-layer atoms relax upwards and all third-layer atoms, again, relax inwards. The ReO2-terminated ReO3 and ZrO2-terminated SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surface band gaps at the Γ–Γ point are always reduced in comparison to their bulk band gap values. The Zr–O chemical bond populations in the SrZrO3, BaZrO3, PbZrO3 and CaZrO3 perovskite bulk are always smaller than those near the ZrO2-terminated (001) surfaces. In contrast, the Re–O chemical bond population in the ReO3 bulk (0.212e) is larger than that near the ReO2-terminated ReO3 (001) surface (0.170e). Nevertheless, the Re–O chem...
Ab initio calculations of BaTiO3 and PbTiO3 (001) and (011) surface structure
We present and discuss the results of calculations of surface relaxations and rumplings for the ͑001͒ and ͑011͒ surfaces of BaTiO 3 and PbTiO 3 using a hybrid B3PW description of exchange and correlation. On the ͑001͒ surfaces, we consider both AO ͑A =Ba or Pb͒ and TiO 2 terminations. In the former case, the surface AO layer is found to relax inward for both materials, while outward relaxations of all atoms in the second layer are found at both kinds of ͑001͒ terminations and for both materials. The surface relaxation energies of BaO and TiO 2 terminations on BaTiO 3 ͑001͒ are found to be comparable, as are those of PbO and TiO 2 on PbTiO 3 ͑001͒, although in both cases the relaxation energy is slightly larger for the TiO 2 termination. As for the ͑011͒ surfaces, we consider three types of surfaces, terminating on a TiO layer, a Ba or Pb layer, or an O layer. Here, the relaxation energies are much larger for the TiO-terminated surface than for the Ba-or Pb-terminated surfaces. The relaxed surface energy for the O-terminated surface is about the same as the corresponding average of the TiO-and Pb-terminated surfaces on PbTiO 3 , but much less than the average of the TiO-and Ba-terminated surfaces on BaTiO 3 . We predict a considerable increase of the Ti-O chemical bond covalency near the BaTiO 3 and PbTiO 3 ͑011͒ surfaces as compared to both the bulk and the ͑001͒ surface.
Ab initio calculations of BaTiO3 and PbTiO3 (001) and (011) surface structures
We present and discuss the results of calculations of surface relaxations and rumplings for the ͑001͒ and ͑011͒ surfaces of BaTiO 3 and PbTiO 3 using a hybrid B3PW description of exchange and correlation. On the ͑001͒ surfaces, we consider both AO ͑A =Ba or Pb͒ and TiO 2 terminations. In the former case, the surface AO layer is found to relax inward for both materials, while outward relaxations of all atoms in the second layer are found at both kinds of ͑001͒ terminations and for both materials. The surface relaxation energies of BaO and TiO 2 terminations on BaTiO 3 ͑001͒ are found to be comparable, as are those of PbO and TiO 2 on PbTiO 3 ͑001͒, although in both cases the relaxation energy is slightly larger for the TiO 2 termination. As for the ͑011͒ surfaces, we consider three types of surfaces, terminating on a TiO layer, a Ba or Pb layer, or an O layer. Here, the relaxation energies are much larger for the TiO-terminated surface than for the Ba-or Pb-terminated surfaces. The relaxed surface energy for the O-terminated surface is about the same as the corresponding average of the TiO-and Pb-terminated surfaces on PbTiO 3 , but much less than the average of the TiO-and Ba-terminated surfaces on BaTiO 3 . We predict a considerable increase of the Ti-O chemical bond covalency near the BaTiO 3 and PbTiO 3 ͑011͒ surfaces as compared to both the bulk and the ͑001͒ surface.
Systematic trends in YAlO3, SrTiO3, BaTiO3, BaZrO3 (001) and (111) surface ab initio calculations
International Journal of Modern Physics B, 2019
The paper presents and discusses the results of performed calculations for YAlO3 (111) surfaces using a hybrid B3LYP description of exchange and correlation. Calculation results for SrTiO3, BaTiO3 and BaZrO3 (111) as well as YAlO3, SrTiO3, BaTiO3 and BaZrO3 (001) surfaces are listed for comparison purposes in order to point out systematic trends common for these four ABO3 perovskite (001) and (111) surfaces. According to performed ab initio calculations, the displacement of (001) and (111) surface metal atoms of YAlO3, SrTiO3, BaTiO3 and BaZrO3 perovskite, upper three surface layers for both AO and BO2 (001) as well as AO3 and B (111) surface terminations, in most cases, are considerably larger than that of oxygen atoms. The YAlO3, SrTiO3, BaTiO3 and BaZrO3 (001) surface energies for both calculated terminations, in most cases, are almost equal. In contrast, the (111) surface energies for both AO3 and B-terminations are quite different. Calculated (111) surface energies always are m...
Nucleation and Atmospheric Aerosols, 2001
We present and discuss results of the calculations for BaTiO 3 and SrTiO 3 surface relaxation with different terminations using a semi-empirical shell model (SM) as well as ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT) formalisms. Using the SM, the positions of atoms in 16 near-surf ace layers placed atop a slab of rigid ions are optimized. This permits us determination of surface rumpling and surface-induced dipole moments (polarization) for different terminations of the (100) and (110) surfaces. We also compare results of the ab initio calculations based on both HF with the DFT-type electron correlation corrections, several DFT with different exchange-correlation functionals, and hybrid exchange techniques. Our SM results for the (100) surfaces are in a good agreement with both our ab initio calculations and LEED experiments. For the (110) surfaces Otermination is predicted to be the lowest in energy.