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 Intercalated architecture of MA2Z4 family layered van der Waals materials with emerging topological, magnetic and superconducting properties

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lei Wang ◽  
Yongpeng Shi ◽  
Mingfeng Liu ◽  
Ao Zhang ◽  
Yi-Lun Hong ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Layer Structure ◽  
Atomic Layer ◽  
Type I ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Valence Electrons ◽  
Nonmagnetic Metals ◽  
Standard Density

AbstractThe search for new two-dimensional monolayers with diverse electronic properties has attracted growing interest in recent years. Here, we present an approach to construct MA2Z4 monolayers with a septuple-atomic-layer structure, that is, intercalating a MoS2-type monolayer MZ2 into an InSe-type monolayer A2Z2. We illustrate this unique strategy by means of first-principles calculations, which not only reproduce the structures of MoSi2N4 and MnBi2Te4 that were already experimentally synthesized, but also predict 72 compounds that are thermodynamically and dynamically stable. Such an intercalated architecture significantly reconstructs the band structures of the constituents MZ2 and A2Z2, leading to diverse electronic properties for MA2Z4, which can be classified according to the total number of valence electrons. The systems with 32 and 34 valence electrons are mostly semiconductors. Whereas, those with 33 valence electrons can be nonmagnetic metals or ferromagnetic semiconductors. In particular, we find that, among the predicted compounds, (Ca,Sr)Ga2Te4 are topologically nontrivial by both the standard density functional theory and hybrid functional calculations. While VSi2P4 is a ferromagnetic semiconductor and TaSi2N4 is a type-I Ising superconductor. Moreover, WSi2P4 is a direct gap semiconductor with peculiar spin-valley properties, which are robust against interlayer interactions. Our study thus provides an effective way of designing septuple-atomic-layer MA2Z4 with unusual electronic properties to draw immediate experimental interest.

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.

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

Theoretical Study of CN Radicals Chemisorption on the Electronic Properties of BC2N Nanotube

2017 ◽  
Vol 48 ◽  
pp. 38-48 ◽  
Author(s):  
Batoul Makiabadi ◽  
Mohammad Zakarianezhad ◽  
Shahin Mohammadzamani
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Method ◽  
Nbo Analysis ◽  
Band Gap Energy ◽  
Functional Method ◽  
Basis Set ◽  
Hybrid Density Functional ◽  
Cn Radicals ◽  
Covalent Nature

In this work, we have investigated the adsorption behavior of the CN radicals on electronic properties of BC2N nanotube (BC2NNT) by means of the B3LYP hybrid density functional method using 6-31G(d) basis set. The results show that CN radicals can be chemically adsorbed on the nanotube. Based on the energy analysis, the most stable position of CN radical on the nanotube is C1 site. Also, the C-side complexes are more stable than the N-side complexes. We investigated the effects of CN radicals adsorption on the electronic properties of the BC2N nanotube. According to our calculations, band gap energy of the BC2NNT decreases with increasing the number of CN radicals. It is predicted that the conductivity and reactivity of nanotube increase by increasing the number of CN radicals. Based on the NBO analysis, in all complexes charge transfer occurs from nanotube to CN radical. The AIM results show that, the Xtube…YCN interaction has covalent nature. Generally, The BC2N nanotube can be used to as sensor for nanodevice 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.

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