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.

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 Combining solid-state NMR spectroscopy with first-principles calculations – a guide to NMR crystallography

2016 ◽  
Vol 52 (45) ◽  
pp. 7186-7204 ◽  
Author(s):  
Sharon E. Ashbrook ◽  
David McKay
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Dft Calculations ◽  
First Principles ◽  
Solid State Nmr ◽  
Nmr Spectra ◽  
First Principles Calculations ◽  
Recent Developments ◽  
Future Potential ◽  
Nmr Crystallography

DFT calculations are an important tool in assigning and interpreting NMR spectra of solids: we discuss recent developments and their future potential in the context of NMR crystallography.

scholarly journals First principles study of structure, electronic and optical properties of Y3Fe5O12 in cubic and trigonal phases

2015 ◽  
Vol 33 (1) ◽  
pp. 169-174 ◽  
Author(s):  
Shen Tao ◽  
Hu Chao ◽  
Dai Hailong ◽  
Yang Wenlong ◽  
Liu Hongchen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Energy Loss ◽  
First Principles ◽  
Structural Parameters ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Direct Band ◽  
Experimental Values

AbstractFirst principles calculations have been performed to investigate the structure, electronic and optical properties of Y3Fe5O12. Both the cubic and trigonal phases have been considered in our calculation. The calculated structural parameters are slightly larger than the experimental values. The band structures show that Y3Fe5O12 in cubic and trigonal phases have direct band gaps of 0.65 and 0.17 eV. The calculations of dielectric function, absorption, extinction coefficient, refractive index, energy loss function and reflectivity are presented.

Two-dimensional layered Janus-In2SeTe/C2N van der Waals heterostructures for photocatalysis and photovoltaics: first-principles calculations

2020 ◽  
Vol 44 (37) ◽  
pp. 16092-16100
Author(s):  
Xiao-Hua Li ◽  
Bao-Ji Wang ◽  
Hui Li ◽  
Xue-Feng Yang ◽  
Rui-Qi Zhao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
First Principles ◽  
Sustainable Energy ◽  
Van Der Waals ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Van Der Waals Heterostructures ◽  
Potential Applications

Through DFT calculations, Janus-In2SeTe/C2N heterostructures are found to have great potential applications in the fields of clean and sustainable energy.

scholarly journals Dissociative adsorption of O2 on negatively charged nitrogen-doped single-walled carbon nanotubes: first-principles calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (87) ◽  
pp. 84155-84163 ◽  
Author(s):  
Divya Srivastava ◽  
Kari Laasonen
Keyword(s):  
Carbon Nanotubes ◽  
Dft Calculations ◽  
First Principles ◽  
Single Walled Carbon Nanotubes ◽  
Dissociative Adsorption ◽  
First Principles Calculations ◽  
Nitrogen Doped ◽  
Single Walled Carbon ◽  
Additional Charges ◽  
Walled Carbon Nanotubes

Spin unrestricted DFT calculations have been used to study the molecular and dissociative adsorption of O2 on achiral substitutional nitrogen-doped single-walled carbon nanotubes with and without additional charges.

The Influence of Surface Reconstruction and C-impurities on Photocatalytic Water Dissociation by TiO2

2003 ◽  
Vol 801 ◽  
Author(s):  
Xiliang Nie ◽  
Karl Sohlberg
Keyword(s):  
Surface Energy ◽  
Band Gap ◽  
First Principles ◽  
Active Sites ◽  
Water Dissociation ◽  
First Principles Calculations ◽  
Surface Band ◽  
Carbon Doped ◽  
Carbon Impurities ◽  
Photoabsorption Spectrum

ABSTRACTTiO2 is well known as a prototype photocatalyst for water dissociation. To understand the mechanism of its photocatalytic water dissociation we performed first-principles calculations. We find that the surface of the catalytically favorable (TiO) termination is very different from the physically favorable (oxygen) termination. The calculated surface energy of the catalytically favorable (TiO) termination is about 10 times larger than that of the physically favorable (oxygen) termination. Analysis of the surface band structure suggests that while O-vacancies are intrinsic active sites for water dissociation into H2 and O2 gas, they are not essential for photocatalytic water dissociation. We also find that carbon impurities decrease the band-gap of TiO2, in agreement with previously reported experimental results. Moreover, we identify the origin of the arcane “double band gap” in carbon doped TiO2. The two onsets seen in the photoabsorption spectrum result from excitations from two of three C p-states within the band gap, not from domains of different composition.

Widely tunable band gaps of graphdiyne: an ab initio study

2014 ◽  
Vol 16 (19) ◽  
pp. 8935-8939 ◽  
Author(s):  
Jahyun Koo ◽  
Minwoo Park ◽  
Seunghyun Hwang ◽  
Bing Huang ◽  
Byungryul Jang ◽  
...  
Keyword(s):  
Ab Initio ◽  
First Principles ◽  
Atomic Layer ◽  
Band Gaps ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Ab Initio Study ◽  
Carbon Networks ◽  
Hybrid Carbon

Functionalization of graphdiyne, a two-dimensional atomic layer of sp–sp2 hybrid carbon networks, was investigated through first-principles calculations.

First-principles study on the geometry and electronic structures of IIIA atoms doped α-Al2O3:VO

2014 ◽  
Vol 92 (10) ◽  
pp. 1135-1140 ◽  
Author(s):  
L. Ao ◽  
J.L. Nie ◽  
X. Xiang ◽  
X.T. Zu ◽  
J. Huang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Oxygen Vacancy ◽  
Electronic Property ◽  
First Principles ◽  
Electronic Structures ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Hexagonal Symmetry ◽  
Α Al2o3 ◽  
Metal Doped

We investigate the geometry and electronic structures of α-Al2O3:VO + AlX systems based on first-principles calculations where VO represents one oxygen vacancy and AlX stands for IIIA atoms (B, Ga, In, and Tl) substituting of one Al atom. It is found that all the aluminates maintain the hexagonal symmetry as the pure α-Al2O3 structure and the lattice parameters a, b, and c are expanded with the increase of the IIIA atoms radius. The electronic property analysis indicates that the band gaps are considerably reduced and the reductions are also related to the radius of doping atoms. But unlike the situation of transition metal doped α-Al2O3 the decreases of the band gap are not due to the spreading of d states, but are mainly owing to the ns states at the bottom of the conduction band.

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