Insights into the Characteristic Gap Level and n-Type Conductivity of Rutile TiO2 from the Hybrid Functional Method

2019 ◽  
Vol 123 (4) ◽  
pp. 2037-2047 ◽  
Author(s):  
Xiaoping Han ◽  
Noureddine Amrane ◽  
Zongsheng Zhang ◽  
Maamar Benkraouda
Keyword(s):  
Functional Method ◽  
Hybrid Functional ◽  
Rutile Tio2 ◽  
Type Conductivity

First-Principles Study of Iron Oxide Polytypes: Comparison of GGA+Uand Hybrid Functional Method

2014 ◽  
Vol 119 (1) ◽  
pp. 556-562 ◽  
Author(s):  
Taedaehyeong Eom ◽  
Hyung-Kyu Lim ◽  
William A. Goddard ◽  
Hyungjun Kim
Keyword(s):  
Iron Oxide ◽  
First Principles ◽  
Functional Method ◽  
Hybrid Functional ◽  
First Principles Study

Study on the optical spectra of the oxygen vacancy in ZnWO4 crystal

2021 ◽  
pp. 2150471
Author(s):  
Gaiping Lian ◽  
Tingyu Liu ◽  
Le Yu
Keyword(s):  
Oxygen Vacancy ◽  
Density Functional ◽  
Defect Formation ◽  
Finite Size ◽  
Optical Spectra ◽  
Functional Method ◽  
Hybrid Functional ◽  
Electron Phonon Coupling ◽  
Correction Scheme ◽  
The Density Functional Theory

ZnWO4 is easy to color, which will reduce the luminous efficiency of the crystal and limit the application of the crystal. In order to study the origin of the color in the crystal, in this paper, the effects of the oxygen vacancy on the optical properties for the ZnWO4 crystal have been studied based on the density functional theory (DFT). The hybrid functional method (HSE) and the finite-size correction scheme (FNV) are used to correct the band edge problem and eliminate the artificial interaction of the charged defects, respectively. On the basis of the corrected defect formation energy, we obtain the optical spectra of the [Formula: see text] and [Formula: see text] centers containing electron-phonon coupling. The calculated absorption and luminescence peaks are at 2.54 eV and 0.79 eV for the [Formula: see text] center and at 2.98 eV and 1.09 eV for the [Formula: see text] center, respectively. The calculated absorption band of the [Formula: see text] center is close to the experimental value of 2.48 eV (500 nm), so we speculate that the coloring of the ZnWO4 crystal is related to the [Formula: see text] center. Meanwhile, the existence of oxygen vacancy makes ZnWO4 crystal to have self-absorption and to increase decay time, which greatly affects the scintillation properties of the crystal.

Investigation of vacancy defects and substitutional doping in AlSb monolayer with double layer honeycomb structure: a first-principles calculation

2021 ◽  
Author(s):  
Asadollah Bafekry ◽  
M. Faraji ◽  
Siavash Karbasizadeh ◽  
Hamad R. Jappor ◽  
Abdolhosseini Sarsari ◽  
...  
Keyword(s):  
Formation Energy ◽  
Bulk Material ◽  
Functional Method ◽  
Honeycomb Structure ◽  
First Principles Calculation ◽  
Ferromagnetic Behavior ◽  
Hybrid Functional ◽  
Vacancy Defects ◽  
Substitutional Doping ◽  
The Stability

Abstract The experimental knowledge of the AlSb monolayer is largely based on the recent publication [Le Qin et al., ACS Nano 2021, 15, 8184], where this monolayer was recently synthesized. Therefore, the aim of our research is to consequently explore the effects of substitutional doping and vacancy point defects on the electronic and magnetic properties of the novel hexagonal AlSb monolayer. Besides experimental reports, the phonon band structure and cohesive energy calculations confirm the stability of the AlSb monolayer. Its direct bandgap has been estimated to be 0.9 eV via the hybrid functional method (HSE), which is smaller than the value of 1.6 eV of bulk material. The majority of vacancy defects and substitutional dopants change the electronic properties of the AlSb monolayer from semiconducting to metallic. Moreover, the Mg_Sb impurity has demonstrated the addition of ferromagnetic behavior to the material. It is revealed through the calculation of formation energy that in Al-rich conditions, the vacant site of V_Sb is the most stable, while in Sb-rich circumstances the point defect of V_Al gets the title. The formation energy has also been calculated for the substitutional dopants, showing relative stability of the defected structures. We undertook this theoretical study to inspire many experimentalists to focus their efforts on AlSb monolayer growth incorporating different impurities. It has been shown here that defect engineering is a powerful tool to tune the properties of novel AlSb two-dimensional monolayer for advanced nanoelectronic applications.

scholarly journals Electronic, Optical, Mechanical and Lattice Dynamical Properties of MgBi2O6: A First-Principles Study

2019 ◽  
Vol 9 (7) ◽  
pp. 1267 ◽  
Author(s):  
Lin Liu ◽  
Dianhui Wang ◽  
Yan Zhong ◽  
Chaohao Hu
Keyword(s):  
First Principles ◽  
Mechanical Stability ◽  
Separation Efficiency ◽  
Elastic Anisotropy ◽  
Functional Method ◽  
Optical Parameters ◽  
Hybrid Functional ◽  
Light Region ◽  
Dynamical Properties ◽  
High Separation

Electronic structure, optical, mechanical, and lattice dynamical properties of the tetragonal MgBi2O6 are studied using a first-principles method. The band gap of MgBi2O6 calculated from the PBE0 hybrid functional method is about 1.62 eV and agrees well with the experimental value. The calculations on elastic constants show that MgBi2O6 exhibits mechanical stability and strong elastic anisotropy. The detailed analysis of calculated optical parameters and effective masses clearly indicate that MgBi2O6 has strong optical response in the visible light region and high separation efficiency of photoinduced electrons and holes.

scholarly journals The electronic properties of impurities (N, C, F, Cl and S) in Ag3PO4: A hybrid functional method study

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Yang Huang ◽  
Tai Ma ◽  
Qing-yuan Chen ◽  
Chao Cao ◽  
Yao He
Keyword(s):  
Electronic Properties ◽  
Functional Method ◽  
Hybrid Functional

scholarly journals Electrical properties and charge compensation mechanisms of Cr-doped rutile, TiO2

2021 ◽  
Author(s):  
Yun Dang ◽  
Xin Li Phuah ◽  
Han Wang ◽  
Bo Yang ◽  
Haiyan Wang ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Oxygen Vacancy ◽  
Electronic Conductivity ◽  
Charge Compensation ◽  
Rutile Tio2 ◽  
Type Conductivity ◽  
Co Doping ◽  
High Electronic Conductivity ◽  
Compensation Mechanisms ◽  
P Type

Ti1−xCrxO2−x/2−δ (0 ≤ x ≤ 0.05) ceramics show high electronic conductivity at low x attributed to oxygen vacancy compensation by co-doping with Ti3+ and Cr3+ ions. At intermediate x, p-type conductivity is attributed to hole location on under-bonded oxygen.

scholarly journals On the influence of water on fragmentation of the amino acid L-threonine

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 250-262
Author(s):  
Laura Baliulyte ◽  
Jelena Tamuliene
Keyword(s):  
Amino Acid ◽  
Appearance Energy ◽  
Polarizable Continuum Model ◽  
Functional Method ◽  
Chemical Compositions ◽  
Hybrid Functional ◽  
Influence Of Water ◽  
Fragment Formation ◽  
Non Local ◽  
Correlation Consistent

Abstract The present study describes the fragmentation of the amino acid L-threonine (C4H9NO3) with and without the inclusion of water influence. The fragmentation of the L-threonine molecule was theoretically studied using the Becke’s three-parameter hybrid functional method by applying the non-local correlation provided by Lee, Yang and Parr (B3LYP) with the correlation consistent triple zeta basis (cc-pVTZ). The polarizable continuum model (PCM) was used to evaluate the influence of water. Fragments were selected based on data from mass spectrometry experiments. The chemical compositions of fragments were identified, and the appearance energy was calculated. Based on the obtained results, we can conclude that water affects the appearance energy, the fragment structure and the fragment formation processes.

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