scholarly journals First-Principles Study on the Effect of Strain on Single-Layer Molybdenum Disulfide

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3127
Author(s):  
Chen Chong ◽  
Hongxia Liu ◽  
Shulong Wang ◽  
Kun Yang
Keyword(s):  
Band Gap ◽  
Molybdenum Disulfide ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Single Layer ◽  
Small Strain ◽  
Structure Changes ◽  
Calculation Results ◽  
Indirect Band Gap

By adopting the first-principles plane wave pseudopotential method based on density functional theory, the electronic structure properties of single-layer MoS2 (molybdenum disulfide) crystals under biaxial strain are studied. The calculation results in this paper show that when a small strain is applied to a single-layer MoS2, its band structure changes from a direct band gap to an indirect band gap. As the strain increases, the energy band still maintains the characteristics of the indirect band gap, and the band gap shows a linear downward trend. Through further analysis of the density of states, sub-orbital density of states, thermodynamic parameters and Raman spectroscopy, it revealed the variation of single-layer MoS2 with strain. This provides a theoretical basis for realizing the strain regulation of MoS2.

First-principles study on the band structure, magnetic and elastic properties of half-metallic Cr2MnAl

2015 ◽  
Vol 29 (24) ◽  
pp. 1550139 ◽  
Author(s):  
Santao Qi ◽  
Chuan-Hui Zhang ◽  
Bao Chen ◽  
Jiang Shen
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Elastic Properties ◽  
Density Functional ◽  
Stable State ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Text Type ◽  
Calculation Results ◽  
Indirect Band Gap

In this study, we have investigated the structural, electronic, magnetic and elastic properties of the full-Heusler [Formula: see text] alloy in the framework of density functional theory with generalized gradient approximation (GGA). The calculated results showed that [Formula: see text] was stable in ferrimagnetic configuration and crystallized in the [Formula: see text]-type structure. From the band structure and density of states calculation results, we concluded that [Formula: see text] belongs to a kind of half-metallic compound with an indirect band gap of 0.37 eV. Immediately thereafter, we have analyzed the origin of half-metallic band gap. The total magnetic moment of [Formula: see text] at the stable state is [Formula: see text] per formula unit, obeying the Slater–Pauling rule [Formula: see text]. In addition, various mechanical properties have been obtained and discussed based on the three principle elastic tensor elements [Formula: see text] and [Formula: see text] for the first time in the present work. We expect that our calculated results may trigger the application of [Formula: see text] in future spintronics field.

The Electronic and Structural Properties of 3C-SiC: A First-Principles Study

2014 ◽  
Vol 971-973 ◽  
pp. 208-212 ◽  
Author(s):  
Ying Gao ◽  
Fu Chun Zhang ◽  
Wei Hu Zhang
Keyword(s):  
Band Gap ◽  
Valence Band ◽  
Conduction Band ◽  
First Principles ◽  
Density Functional ◽  
Energy Splitting ◽  
Functional Theory ◽  
Structure Density ◽  
Indirect Band Gap ◽  
Electronic And Structural Properties

We investigate geometric structure, electronic structure and ground properties of 3C-SiC as obtained form first-principles calculations based on density functional theory with the LDA, GGA, B3LYP and HSE06 method. After comparative analysis of the total energy, band structure, density of states and the bulk modulus, we found that 3C-SiC was an indirect band gap semiconductor, the top of valence band was located at Γ point, and the bottom of conduction band was located at X point. The indirect band gap of 3C-SiC calculated by LDA, GGA, B3LYP and HSE06 was 1.34 eV, 1.44 eV, 2.88 eV and 2.26 eV, respectively. Especially for B3LYP and HSE06 methods which clearly calculated the energy splitting and the energy dispersion of both the top of valence band and the bottom of conduction band was in well agreement with the experimental data. These results will provide theoretical basis for the design and application of SiC materials.

Electronic structure and magnetic ordering in gadolinium-doped AlGaN from LSDA + U calculations

2018 ◽  
Vol 07 (03) ◽  
pp. 1850019 ◽  
Author(s):  
S. Belhachi ◽  
S. Amari ◽  
B. Bouhafs
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Magnetic Ordering ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Indirect Band Gap

We present first-principles calculations of the structural, electronic and magnetic properties of Gd-doped [Formula: see text] based on the density functional theory within [Formula: see text] schemes. It is found that Gd atom favors substituting for Al site. Compared with undoped [Formula: see text], the Gd-doped [Formula: see text] has become an indirect band gap semiconductor of reduced band gap. The magnetic moment [Formula: see text] per molecule mainly comes from Gd ion with little contribution from the Ga, Al and N atoms. It is confirmed that the ferromagnetic configuration is stable for [Formula: see text]. It is found also that there is hybridization between the forbital of the Gd atom and the [Formula: see text] orbital of the N atom.

scholarly journals First Principles Study of Thermoelectric Properties of Skutterudites: Ir4Sb12 and Ca0.04Ir4Sb12

2020 ◽  
Vol 6 (2) ◽  
pp. 1-9
Author(s):  
B. Bhattarai ◽  
T. Dahal ◽  
N. P. Adhikari
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Density Of States ◽  
First Principles ◽  
Figure Of Merit ◽  
Density Functional ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Metallic Behavior ◽  
Maximum Value

First – principles calculations to study thermal and electrical properties of pristine and calcium filled skutterudite Ir4Sb12 has been carried out. Density of states (DOS) and band-structure calculations are based on Density Functional Theory (DFT) within Generalized Gradient Approximation (GGA). Transport properties are calculated using BoltzTrap software packages. Volume optimization is carried out on the basis of Murnaghan equation of states. The optimized lattice parameter of pristine Ir4Sb12 is found to be 9.4243 Å and that of calcium filled Ir4Sb12 is found to be 9.4949 Å. Our calculation shows that pristine Ir4Sb12 is a p-type of semiconductor with a narrow PBE-GGA band gap of 0.25 eV. After filling calcium, the band gap is reduced to zero showing the metallic behavior of filled compound. Band structure, density of states, variations of electrical and thermal conductivities with temperature and Seebeck coefficient show that calcium filled Ir4Sb12 has a metallic character. At Fermi level, the maximum value of thermoelectric figure of merit of unfilled Ir4Sb12 compound at temperature 400K is found to be 0.5. At the same temperature thermoelectric figure of merit calcium filled Ca0.04Ir4Sb12 is found to be around 0.03. The maximum value of of Ca filled Ca0.04Ir4Sb12 at 1000K is computed around 0.1.

Increased Malleability in Tetragonal Zrx Ti1−x O2 Ternary Alloys: First-Principles Approach

2017 ◽  
Vol 72 (6) ◽  
pp. 567-572
Author(s):  
F. Ayedun ◽  
P.O. Adebambo ◽  
B.I. Adetunji ◽  
V.C. Ozebo ◽  
J.A. Oguntuase ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Ternary Alloys ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Direct Band ◽  
Indirect Band Gap ◽  
Projector Augmented Wave ◽  
Alloying Effects

AbstractTetragonal phase of ZrxTi1−xO2ternary alloys is studied using generalized gradient approximation (GGA) projector augmented wave-based density functional theory (DFT). The calculations are used to characterize alloying effects of Zr substituting Ti in tutile TiO2. Band gap calculations show a direct band gap atx=0, while at other concentrations, an indirect band gap is observed. Electronic structure analysis shows that Zr alloying is capable of lowering the band gap transition of ZrxTi1−xO2atx=1 by the presence of an impurity state of transition metal Zr 5S2on the upper edge of the valence band. The addition of Zr also results in the corresponding increment in lattice constant with the material becoming more ductile and malleable.

scholarly journals First-principles study of C cites vacancy defects in water adsorbed Graphene

2020 ◽  
pp. 19-29
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Band Gap ◽  
Density Of States ◽  
Magnetic Moment ◽  
First Principles ◽  
Density Functional ◽  
Partial Density ◽  
Dangling Bonds ◽  
Graphene Surface ◽  
Vacancy Defects

 The electronic and magnetic properties of water adsorbed graphene (wad – G), single carbon (1C) atom vacancy defects in water adsorbed graphene (1Catom-vacancy – wad – G) and double carbon (2C) atoms vacancy defects in water adsorbed graphene (2Catom-vacancy – wad – G) materials are studied by first-principles calculations within the frame work of density functional theory (DFT) using computational tool Quantum ESPRESSO (QE) code. We have calculated the binding energy of wad – G, 1Catom-vacancy – wad – G and 2Catom-vacancy – wad – G materials, and then found that non-defects geometry is more compact than vacancy defects geometries. From band structure calculations, we found that wad – G is zero band gap semiconductor, but 1Catom-vacancy – wad – G and, 2Catom-vacancy – wad – G materials have metallic properties. Hence, zero band gap semiconductor changes to metallic nature due to C sites vacancy defects in its structures. We have investigated the magnetic properties of wad – G and its C sites vacancy defects materials by using Density of States (DOS) and Partial Density of States (PDOS) calculations. We found that wad – G is non- magnetic material. 1C atom vacancy defects in graphene surface of wad – G is induced magnetization by the re-bonding of two dangling bonds and acquiring significant magnetic moment (0.11 µB/ cell) through remaining unsaturated dangling bond. But, 2C atoms vacancy defects in graphene surface of wad – G induced low value of magnetic moment (+0.03 µB/ cell) than 1C atom vacancy defects in structure, which is due to no dangling bonds present in the structure. Therefore, non-magnetic, wad – G changes to magnetic, 1Catom-vacancy – wad – G and, 2Catom-vacancy – wad – G materials due to C sites vacancy defects in wad – G structure. The 2p orbital of carbon atoms has main contribution of magnetic moment in defects structures.

First principles calculations of electronic and optical properties of Zr-doped La2O3

2013 ◽  
Vol 91 (10) ◽  
pp. 801-807 ◽  
Author(s):  
Changpeng Chen ◽  
Jianxiong Xie ◽  
Shuibo Chen ◽  
Yanli Li
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Visible Region ◽  
Potential Candidate ◽  
First Principles Calculations ◽  
Additional Absorption ◽  
Level Shifts ◽  
Calculation Results

Based on the density functional pseudopotential method, the structural properties, the band structure, the density of states, and the optical properties of pure and Zr-doped La2O3 were calculated. The calculation results indicate that the defect of La (Zr) exists steadily with a certain solubility. Zr substitution of the La sites induces effective reduction of the band gap of La2O3, the band gap being continuously reduced when increasing Zr doping level. The Fermi energy level shifts to the conduction band and exhibits metal-like characteristic after the Zr atom is introduced. The calculated optical properties indicate that red shifts are revealed in both the imaginary part of the dielectric function and the absorption spectra corresponding to the change of band gaps. Moreover, additional absorption is observed in the visible region, which implies that Zr-doped La2O3 might be a potential candidate for photoelectrical application. The calculation results are consistent with experimental results that have been reported.

First-Principles Calculations on Pure and Y-Doped Anatase TiO2

2013 ◽  
Vol 562-565 ◽  
pp. 1166-1170 ◽  
Author(s):  
Xiong Tang ◽  
Lan Fang Yao ◽  
Xin Pei Yan ◽  
Jun Long Kang
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Partial Density ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Calculation Results ◽  
Band Gap Narrowing

Using the First principles calculations, the crystal structure, band gap, total and partial density of states (DOS) of anatase TiO2and anatase TiO2doped with Yttrium were calculated by a plane-wave pseudopotential (PWPP) method based on density functional theory (DFT). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization was employed to calculate them. From the calculation results, the band gap of anatase TiO2and Y3+doped TiO2are about 2.15eV and 0.86eV. The calculated results demonstrated that the mixing of Yttrium (Y) dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

scholarly journals Band Structure of Sr Doped into Bulk Wurtzite ZnO: A DFT Study.

2021 ◽  
pp. 10-17
Author(s):  
Abdalla Abdelrahman Mohamed ◽  
Tasneem Babiker Abdalrahman
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Band Gap Energy ◽  
Unit Cell Parameters ◽  
Lattice Volume ◽  
Cell Parameters ◽  
Structural And Electronic Properties ◽  
Direct Band ◽  
Indirect Band Gap

This work investigates the structural and electronic properties of pure and Sr-doped ZnO using first principles density functional calculations (DFT). The calculations were carried out using GGA-BLYP functional. This functional underestimates the band gap value in semiconductors but does not affect the accuracy of the related properties of the crystals. The Sr-doping caused increase in lattice volume and slight distortions at the unit cell parameters in a wurtzite structure. The doping process presented increase in the band-gap energy Eg at low percentages 25%, 37.5% and 50% with indirect bang gap and direct band gap at high percentages 62.5%, 75%, 87.5% and 100%.which we can called it wide indirect band gap. These results can be use as a foundation for more in depth calculations which can be used on optical and Photo-catalytic applications.

scholarly journals First Principles Study of Electronic and Optical Properties of Pristine and X (Cu, Ag And Au) Doped BiOBr

2018 ◽  
Vol 22 (2) ◽  
pp. 63-69 ◽  
Author(s):  
Samir Paudel ◽  
Puspa Raj Adhikari ◽  
Om Prakash Upadhyay ◽  
Gopi Chandra Kaphle ◽  
Anurag Srivastava
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Ab Initio Approach ◽  
Indirect Band Gap ◽  
Standard Density

The electronic structures and optical properties of pristine BiOBr and Cu, Ag and Au doped BiOBr have been analyzed by using a standard density functional theory based ab-initio approach employing generalized gradient approximation through revised Perdew Burke Ernzerhoff type parameterization. The calculation shows that both the doped and pristine BiOBr have indirect band gap, the band gap of the pristine BiOBr found 2.22eV, whereas band gap significantly reduced after doping Cu, Ag and Au on BiOBr. The band gap of Cu, Ag and Au doped BiOBr are 1.2eV, 0.9eV and 1.76eV respectively. The optical properties have been studied through dielectric function, both pure and doped BiOBr shows anisotropic nature. Journal of Institute of Science and TechnologyVolume 22, Issue 2, January 2018, page: 63-69 

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