Comparison of hydrogen vacancies in KDP and ADP crystals: a combination of density functional theory calculations and experiment

2019 ◽  
Vol 21 (11) ◽  
pp. 6186-6197 ◽  
Author(s):  
Tingting Sui ◽  
Yafei Lian ◽  
Mingxia Xu ◽  
Lisong Zhang ◽  
Yanlu Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Absorption ◽  
Rapid Growth ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Theoretical Method ◽  
Functional Theory ◽  
Calculation Results ◽  
Growth Method

KDP and ADP crystals were grown by the rapid growth method, and the origin of the extra optical absorption in both crystals has been explored by theoretical method. The calculation results well explain the experimental phenomenon, and confirm the existence of hydrogen vacancies in both crystals.

Effects of S/Ce-codoping on electronic structures and optical properties of anatase TiO2 from density functional theory calculations

2015 ◽  
Vol 29 (35n36) ◽  
pp. 1550249
Author(s):  
Shi Wen Zhou ◽  
Jian Liu ◽  
Ping Peng ◽  
Wen Qin Chen
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Density Functional ◽  
Defect Formation ◽  
Dipole Moments ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Light Region ◽  
Rich Condition

The electronic and optical properties of S- and/or Ce-(co)doped anatase titanium dioxide (TiO2) are investigated using density functional theory plus U (DFT[Formula: see text]U) calculations. The optimized total energy suggests that TiO2 codoping by Ce and S favours the configuration of one substitutional Ce atom occupied on a Ti site with one substitutional S atom either on its nearest neighboring O or Ti site. The calculated results show that all doping configurations exhibit remarkable red-shift and excellent photocatalytic properties compared with pure TiO2. These reinforced features can mainly be ascribed to the appearance of S [Formula: see text] states in the top of valence band (VB) and Ce [Formula: see text] states in the bottom of conduction band (CB) as well as the contribution from the increasing octahedral dipole moments. The synergetic effects of cationic Ce and anionic S can extend optical absorption edge, which results in higher absorption coefficient in the visible light region than that of the anionic S monodoping and cationic Ce monodoping case; in the same time, decreasing the codoping concentration leads to reduced optical absorption. Additionally, Ce and S as cations incorporating into TiO2 lattices can induce stronger redox potential with a lower defect formation energy under O-rich condition compared with other doping systems.

scholarly journals Screening of II-IV-V2 Materials for Photovoltaic Applications Based on Density Functional Theory Calculations

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 883
Author(s):  
Byeong-Hyeon Jeong ◽  
Minwoo Jeong ◽  
Youbin Song ◽  
Kanghyeon Park ◽  
Ji-Sang Park
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Energy Difference ◽  
Stacking Sequence ◽  
Electronic Band ◽  
Functional Theory ◽  
Photovoltaic Applications ◽  
Calculation Results

The relative stability of polymorphs and their electronic structure was investigated for II-IV-V2 materials by using first-principles density functional theory calculations. Our calculation results show that, for Zn-, Cd-, and Be-containing compounds, nitrides favor the 2H polymorph with AB stacking sequence; however, phosphides, arsenides, and antimonides are more stable in the 3C polymorph with the ABC stacking sequence. The electronic band gap of materials was calculated by using hybrid density functional theory methods, and then materials with an ideal band gap for photovoltaic applications were chosen. The experimental synthesis of the screened materials is reported, except for CdSiSb2, which was found to be unstable in our calculation. The absorption coefficient of the screened materials, especially ZnGeAs2, was high enough to make thin-film solar cells. The higher stacking fault energy in ZnGeAs2 than the others is consistent with the larger formation energy difference between the 2H and 3C polymorphs.

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

scholarly journals Tensor-structured algorithm for reduced-order scaling large-scale Kohn–Sham density functional theory calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chih-Chuen Lin ◽  
Phani Motamarri ◽  
Vikram Gavini
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
System Size ◽  
Real Space ◽  
Functional Theory ◽  
Reduced Order ◽  
Separable Approximation ◽  
Tensor Basis

AbstractWe present a tensor-structured algorithm for efficient large-scale density functional theory (DFT) calculations by constructing a Tucker tensor basis that is adapted to the Kohn–Sham Hamiltonian and localized in real-space. The proposed approach uses an additive separable approximation to the Kohn–Sham Hamiltonian and an L1 localization technique to generate the 1-D localized functions that constitute the Tucker tensor basis. Numerical results show that the resulting Tucker tensor basis exhibits exponential convergence in the ground-state energy with increasing Tucker rank. Further, the proposed tensor-structured algorithm demonstrated sub-quadratic scaling with system-size for both systems with and without a gap, and involving many thousands of atoms. This reduced-order scaling has also resulted in the proposed approach outperforming plane-wave DFT implementation for systems beyond 2000 electrons.

scholarly journals Polymorphs of Rb3ScF6: X-ray and Neutron Diffraction, Solid-State NMR, and Density Functional Theory Calculations Study

2021 ◽  
Vol 60 (8) ◽  
pp. 6016-6026
Author(s):  
Aydar Rakhmatullin ◽  
Maxim S. Molokeev ◽  
Graham King ◽  
Ilya B. Polovov ◽  
Konstantin V. Maksimtsev ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Neutron Diffraction ◽  
Solid State Nmr ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
X Ray

Graphene adlayer growth between nonepitaxial graphene and Ni(111) substrate: a promising theoretical scheme

2020 ◽  
Author(s):  
Lijuan Meng ◽  
Jinlian Lu ◽  
Yujie Bai ◽  
Lili Liu ◽  
Tang Jingyi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Chemical Vapor Deposition ◽  
Molecular Dynamics Simulations ◽  
Vapor Deposition ◽  
Density Functional ◽  
Chemical Vapor ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Dynamics Simulations

Understanding the fundamentals of chemical vapor deposition bilayer graphene growth is crucial for its synthesis. By employing density functional theory calculations and classical molecular dynamics simulations, we have investigated the...

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