scholarly journals Comparative Ab Initio Calculations of ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) Surfaces

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 745 ◽  
Author(s):  
Roberts I. Eglitis ◽  
Juris Purans ◽  
Jevgenijs Gabrusenoks ◽  
Anatoli I. Popov ◽  
Ran Jia
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Bond ◽  
First Principles Calculations ◽  
Surface Band ◽  
Bond Population ◽  
Calculation Results ◽  
First Time ◽  
Bulk Band ◽  
Crystal Bulk

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 chemical bond population between the Re atom located on the ReO2-terminated ReO3 (001) surface upper layer and the O atom located on the ReO2-terminated ReO3 (001) surface second layer (0.262e) is the largest.

scholarly journals Comparative Hybrid Hartree-Fock-DFT Calculations of WO2-Terminated Cubic WO3 as Well as SrTiO3, BaTiO3, PbTiO3 and CaTiO3 (001) Surfaces

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 455
Author(s):  
R. I. Eglitis ◽  
Juris Purans ◽  
Ran Jia
Keyword(s):  
Dft Calculations ◽  
Chemical Bond ◽  
First Principles ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Surface Band ◽  
Hartree Fock ◽  
Bond Population ◽  
Bulk Band ◽  
Crystal Bulk

We performed, to the best of our knowledge, the world’s first first-principles calculations for the WO2-terminated cubic WO3 (001) surface and analyzed the systematic trends in the WO3, SrTiO3, BaTiO3, PbTiO3 and CaTiO3 (001) surface ab initio calculations. According to our first principles calculations, all WO2 or TiO2-terminated WO3, SrTiO3, BaTiO3, PbTiO3 and CaZrO3 (001) surface upper-layer atoms relax inwards towards the crystal bulk, while all second-layer atoms relax upwards. The only two exceptions are outward relaxations of first layer WO2 and TiO2-terminated WO3 and PbTiO3 (001) surface O atoms. The WO2 or TiO2-terminated WO3, SrTiO3, BaTiO3, PbTiO3 and CaTiO3 (001) surface-band gaps at the Γ–Γ point are smaller than their respective bulk-band gaps. The Ti–O chemical bond populations in the SrTiO3, BaTiO3, PbTiO3 and CaTiO3 bulk are smaller than those near the TiO2-terminated (001) surfaces. Conversely, the W–O chemical bond population in the WO3 bulk is larger than near the WO2-terminated WO3 (001) surface.

Ab Initio Calculations for Grain Boundaries in Covalent Ceramics

1996 ◽  
Vol 458 ◽  
Author(s):  
Masanori Kohyama
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Grain Boundaries ◽  
First Principles ◽  
Localized States ◽  
Edge States ◽  
Bulk Diamond ◽  
First Time ◽  
Bulk Band

ABSTRACTAb initio calculations of grain boundaries in SiC have been performed for the first time by using the first-principles molecular dynamics (FPMD) method. Four-fold coordinated models of polar and non-polar interfaces of the {122}Σ = 9 boundary in SiC have been examined. Interfacial C-C and Si-Si wrong bonds have bond lengths and bond charges similar to those in bulk diamond and Si. The C-C bonds generate greatly localized states at the valence-band edges, which have features similar to the bulk band-edge states of diamond. The wrong bonds have significant effects on the properties of grain boundaries in SiC.

scholarly journals Systematic trends in YAlO3, SrTiO3, BaTiO3, BaZrO3 (001) and (111) surface ab initio calculations

2019 ◽  
Vol 33 (32) ◽  
pp. 1950390 ◽  
Author(s):  
Roberts Eglitis ◽  
J. Purans ◽  
A. I. Popov ◽  
Ran Jia
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Surface Layers ◽  
Surface Energies ◽  
Metal Atoms ◽  
Calculation Results ◽  
Surface Metal ◽  
Exchange And Correlation ◽  
Oxygen Atoms

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 much larger than the (001) surface energies. As follows from performed ab initio calculations for YAlO3, SrTiO3, BaTiO3 and BaZrO3 perovskites, the AO- and BO2-terminated (001) as well as AO3- and B-terminated (111) surface bandgaps are almost always reduced with respect to their bulk bandgap values.

scholarly journals Dynamics Studies of Nitrogen Interstitial in GaN from Ab Initio Calculations

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3627
Author(s):  
Huan He ◽  
Wenbo Liu ◽  
Pengbo Zhang ◽  
Wenlong Liao ◽  
Dayin Tong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Separation Distance ◽  
Semiconductor Materials ◽  
Stable Configuration ◽  
Anisotropic Behavior ◽  
Out Of Plane ◽  
First Time ◽  
Good Agreement

Understanding the properties of defects is crucial to design higher performance semiconductor materials because they influence the electronic and optical properties significantly. Using ab initio calculations, the dynamics properties of nitrogen interstitial in GaN material, including the configuration, migration, and interaction with vacancy were systematically investigated in the present work. By introducing different sites of foreign nitrogen atom, the most stable configuration of nitrogen interstitial was calculated to show a threefold symmetry in each layer and different charge states were characterized, respectively. In the researches of migration, two migration paths, in-plane and out-of-plane, were considered. With regards to the in-plane migration, an intermediated rotation process was observed first time. Due to this rotation behavior, two different barriers were demonstrated to reveal that the migration is an anisotropic behavior. Additionally, charged nitrogen Frenkel pair was found to be a relatively stable defect complex and its well separation distance was about 3.9 Å. Part of our results are in good agreement with the experimental results, and our work provides underlying insights of the identification and dynamics of nitrogen interstitial in GaN material. This study of defects in GaN material is useful to establish a more complete theory and improve the performance of GaN-based devices.

The Chemical Bond in Carbonyl and Sulfinyl Groups Studied by Soft X-ray Spectroscopy and ab Initio Calculations

ChemPhysChem ◽  
2012 ◽  
Vol 13 (13) ◽  
pp. 3106-3111 ◽  
Author(s):  
Kaan Atak ◽  
Nicholas Engel ◽  
Kathrin M. Lange ◽  
Ronny Golnak ◽  
Malte Gotz ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Bond ◽  
X Ray

Electronic and magnetic properties of BN nanosheet superlattices: First-principles calculations

2018 ◽  
Vol 32 (31) ◽  
pp. 1850348
Author(s):  
Xiao-Qin Feng ◽  
Hong-Xia Lu ◽  
Jian-Ming Jia ◽  
Chang-Shun Wang
Keyword(s):  
Magnetic Properties ◽  
Boron Nitride ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electronic Properties ◽  
First Principles ◽  
First Principles Calculations ◽  
Electronic And Magnetic Properties ◽  
Boron Nitride Nanosheet

Systematic ab initio calculations reveal that the electronic and magnetic properties are modified by superlattices of zigzag and armchair Boron nitride nanosheet (BNNS). Superlattices are constructed by partially hydrogenated B and N atoms of BNNS. The results show that only no more than half N atoms hydrogenated superlattices are antiferromagnetic. The electronic properties of zigzag BN nanosheet superlattices depend on the degree of hydrogenation of N atoms sensitively. As a result, changing the degree of hydrogenation of N atoms results in the transition from semiconductor to metal.

Ab initio calculations of chemical bond parameters and the band structure of a two-dimensional system: Graphene/MnO(001)

2011 ◽  
Vol 52 (5) ◽  
pp. 849-860 ◽  
Author(s):  
V. V. Ilyasov ◽  
D. A. Velikokhatskii ◽  
I. V. Ershov ◽  
I. Ya. Nikiforov ◽  
T. P. Zhdanova
Keyword(s):  
Band Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Bond ◽  
Dimensional System ◽  
Two Dimensional ◽  
Two Dimensional System

Assignment of Raman-active vibrational modes of tetragonal mackinawite: Raman investigations and ab initio calculations

RSC Advances ◽  
2014 ◽  
Vol 4 (49) ◽  
pp. 25827-25834 ◽  
Author(s):  
Y. El Mendili ◽  
B. Minisini ◽  
A. Abdelouas ◽  
J.-F. Bardeau
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Direct Methods ◽  
Vibrational Modes ◽  
Dispersion Correction ◽  
Density Functional Perturbation Theory ◽  
Calculation Results

We report on the first assignment of the Raman-active vibrational modes of mackinawite using Density Functional Perturbation Theory and direct methods with BLYP + dispersion correction. Based on experimental data and calculation results, the Raman bands were assigned as 236 cm−1 (B1g), 256 cm−1 (Eg), 376 cm−1 (A1g) and 395 cm−1 (Eg).

Nature of the Chemical Bond of Aqueous Fe2+ Probed by Soft X-ray Spectroscopies and ab Initio Calculations

2013 ◽  
Vol 117 (41) ◽  
pp. 12613-12618 ◽  
Author(s):  
Kaan Atak ◽  
Sergey I. Bokarev ◽  
Malte Gotz ◽  
Ronny Golnak ◽  
Kathrin M. Lange ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Bond ◽  
X Ray
Sign in / Sign up

Export Citation Format

Share Document