scholarly journals A Newly Developed Dispersive Interaction Approach, DFT-D3, To The Three-Dimensional Topological Host Material Sb2Te3

2021 ◽  
Author(s):  
Nishant Shukla ◽  
Pawan Chetri ◽  
Gazi A. Ahmed
Keyword(s):  
Density Of States ◽  
Lattice Structure ◽  
Three Dimensional ◽  
Surface States ◽  
Partial Density ◽  
Total Density ◽  
Energy Bands ◽  
Layered Semiconductor ◽  
Interaction Approach ◽  
Quantum Espresso

Abstract Antimony Telluride (Sb2Te3), a topological insulator is a layered semiconductor material with hexagonal unit cell similar to graphene. The characteristic presence of their conducting edges or surfaces with self-induced protection, promise for remarkable future applications. In this exertion based on the first principle approach, the structural and electronic properties of Sb2Te3 compound have been investigated for both without and with spin orbit coupling (SOC). Lattice structure, band structure, total density of states (TDOS), partial density of states (PDOS), energy bands of surface states are determined within Quantum Espresso simulation package. Furthermore, dispersive interactions, induced due to the presence of van-der-Waals forces have also been taken care of. The newly developed method of DFT-D3 has been incorporated for accurate predictions of band gap and lattice parameters. A proficient model, The Slab Model, has been used to observe the presence of single Dirac cone on the surface. To our knowledge, our theoretical investigations are valid and are found to be congruous with the observed data.

Electronic Properties of Calcium and Zirconium Co-Doped BaTiO3

2020 ◽  
Vol 1010 ◽  
pp. 308-313
Author(s):  
Akeem Adekunle Adewale ◽  
Abdullah Chik ◽  
Ruhiyuddin Mohd Zaki
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Of States ◽  
Energy Band ◽  
Density Functional ◽  
Partial Density ◽  
Total Density ◽  
Energy Band Gap ◽  
Wide Energy ◽  
Direct Band

Barium titanate (BaTiO3) is a perovskite based oxides with many potential application in electronic devices. From experimental report BaTiO3 has wide energy band gap of about 3.4 eV which by doped with Ca and Zr at A- and B- sites respectively can enhance their piezoelectric properties. Using first principles method within the density functional theory (DFT) as implement in Quantum Espresso (QE) with the plane wave pseudo potential function, the influence of the Ca and Zr doping in BaTiO3 are studied via electronic properties: band structure, total density of states (TDOS) and partial density of states (PDOS). The energy band gap calculated was underestimation which is similar to other DFT work. Two direct band gap where observed in Ba0.875Ca0.125Ti0.875Zr0.125O3 sample at Γ- Γ (2.31 eV) and X- X (2.35 eV) symmetry point.

First Principles Study on Adsorption for Different Concentration of H2S on Fe(100)

2014 ◽  
Vol 1015 ◽  
pp. 521-525 ◽  
Author(s):  
Qiang Zhang ◽  
Ping Jun Hu ◽  
Qiang Luo ◽  
Yi Qiu ◽  
Zeng Ling Ran
Keyword(s):  
Density Of States ◽  
First Principles ◽  
Function Theory ◽  
Surface Adsorption ◽  
Density Function Theory ◽  
Partial Density ◽  
Total Density ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Total Density Of States

Using the first principles method, which is based on the density function theory (DFT), the structures and electronic properties for different concentration of H2S are adsorbed on the Fe (100) surface, and their molecular orbital and absorption energies were calculated with the generalized gradient approximation. The results show that, whether one or two molecules of H2S adsorpted Fe (100) surface, adsorption of single molecules Fe (100) surface partial density of states between pure Fe (100) and two molecules, and the total density of states is mainly composed of 3d electronic contribution.

First-Principles Study of Electronic Structure and Optical Properties of V-Doped CrSi2

2015 ◽  
Vol 1104 ◽  
pp. 125-130 ◽  
Author(s):  
Fang Gui ◽  
Shi Yun Zhou ◽  
Wan Jun Yan ◽  
Chun Hong Zhang ◽  
Shao Bo Chen
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Density Of States ◽  
Density Functional ◽  
Partial Density ◽  
Optical Parameters ◽  
Total Density ◽  
Type Semiconductor ◽  
Refractive Index Increase ◽  
P Type

The electronic structure and optical properties of V-doped CrSi2 have been calculated by using the first-principle peudo-potential plane-wave method based on the density functional theory.The parameters and properties of structure were given and the theory data were offered to research the effect of V doping into CrSi2. The calculations of energy band structure, total density of states, partial density of states of V-doped CrSi2were analysed. Fermi level enters into valence band which makes the V-doped CrSi2to be p-type semiconductor that improves the electrical conductivity of material. Additionally, the optical parameters of V-doped CrSi2were also discussed. It was found that both static dielectric constant and static refractive index increase after doping.

Physical properties of ThCr2Si2-type Rh-based compounds ARh2Ge2(A = Ca, Sr, Y and Ba): DFT based first-principles investigation

2018 ◽  
Vol 32 (32) ◽  
pp. 1850357 ◽  
Author(s):  
M. U. Salma ◽  
Md. Atikur Rahman
Keyword(s):  
Thermal Conductivity ◽  
Density Of States ◽  
Density Functional ◽  
Partial Density ◽  
Total Density ◽  
Coating Materials ◽  
Metallic Behavior ◽  
Density Maps ◽  
Debye Temperatures ◽  
Low Energies

In this paper, we have explored the physical, mechanical, chemical bonding, dialectical and thermodynamic properties of ARh2Ge2 (A = Ca, Sr, Y and Ba) theoretically for the first time. This investigation has been completed by density functional theory (DFT) calculations with the help of CASTEP code. The structural optimized factors of ARh2Ge2 (A = Ca, Sr, Y and Ba) are in excellent concurrence with the existing experimental data. The observed elastic constants are positive and prove the mechanical constancy for all these compounds. The calculated Pugh’s ratio and Poisson’s ratio show the ductile behaviors of Ca/YRh2Ge2 and brittleness behaviors of Sr/BaRh2Ge2, whereas the Cauchy pressure indicates the ductility for all these phases. The anisotropic factors, universal anisotropy indicator and fraction of anisotropy in compression and shear ensure the elastically anisotropic nature for all these phases. Bulk modulus and hardness values indicate that Sr/BaRh2Ge2 are soft and easily machinable in comparison with Y/CaRh2Ge2. The analysis of the band structure diagrams as well as density of states (total density of states and partial density of states) evidence the metallic behavior for all the compounds. The analysis of Mulliken bond populations and charge density maps give the existence of covalent and metallic bonding in these compounds. The optical properties point out that all phases can be used as coating materials at low energies. For all the phases the Debye temperatures have been calculated via elastic constant data. We have also evaluated the minimum thermal conductivity for these compounds. All compounds possess the relatively low minimum thermal conductivity with the low value of Debye temperatures which also evidence that all compounds could be applied like thermal fence covering material.

Elastic Properties and Electronic Structure of WS2 under Pressure from First-principles Calculations

2017 ◽  
Vol 72 (4) ◽  
pp. 295-301 ◽  
Author(s):  
Li Li ◽  
Zhao-Yi Zeng ◽  
Ting Liang ◽  
Mei Tang ◽  
Yan Cheng
Keyword(s):  
Density Of States ◽  
First Principles ◽  
External Pressure ◽  
Band Gaps ◽  
Partial Density ◽  
Total Density ◽  
Transition Metal Dichalcogenide ◽  
First Principles Calculations ◽  
First Time ◽  
Total Density Of States

AbstractThe influence of pressure on the elastic and mechanical properties of the hexagonal transition-metal dichalcogenide WS2 is investigated using the first-principles calculations. With the increase in pressure, the lattice parameters and the volume of WS2 decrease, which is exactly in agreement with the available experimental data and other calculated results. The elastic constants Cij, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson’s ratio σ of WS2 also increase with pressure. At last, for the first time, the band gaps of energy, the partial density of states, and the total density of states under three different pressures are obtained and analysed. It is found that the band gap of WS2 decreases from 0.843 to 0 eV when the external pressure varies from 0 to 20 GPa, which implies that WS2 may transform from semiconductors to semimetal phase at a pressure about 20 GPa.

ELECTRONIC STRUCTURE CALCULATIONS FOR MoSe2 USING EXTENDED HUCKEL TIGHT-BINDING METHOD

2004 ◽  
Vol 18 (01) ◽  
pp. 35-44 ◽  
Author(s):  
DONALD H. GALVAN
Keyword(s):  
Electronic Structure ◽  
Density Of States ◽  
Population Analysis ◽  
Tight Binding ◽  
Electronic Structure Calculations ◽  
Total Density ◽  
Mulliken Population Analysis ◽  
Energy Bands ◽  
Mulliken Population ◽  
Structure Calculations

To gain insight into the electronic properties of MoSe 2 (molybdenum selenide, also known as drysdallite), electronic structure calculations, total and projected density of states, crystal orbital overlap population and Mulliken population analysis were performed. The calculated energy bands depict a semiconductor behavior with a direct gap (at K) of 0.91 eV and an indirect gap (from Γ to K) of 3.6 eV, respectively. Total and projected density of states provided information about the contribution from each orbital of each atom to the total density of states. Moreover, the bonding strength between some atoms within the unit cell was obtained. Mulliken population analysis corroborates the electron filling of the Mo dz2 orbitals in agreement with another experimental and theoretical results.

scholarly journals Study on Electronic and Optical Properties of Graphene Oxide Under an External Electric Field From First-principles

2021 ◽  
Author(s):  
Abdehafid Najim ◽  
Omar BAJJOU ◽  
Mustapha BOULGHALLAT ◽  
Mohammed Khenfouch ◽  
Khalid Rahmani
Keyword(s):  
Optical Properties ◽  
Graphene Oxide ◽  
Electric Field ◽  
Band Gap ◽  
External Electric Field ◽  
Density Of States ◽  
Density Functional ◽  
Partial Density ◽  
Total Density ◽  
Electronic And Optical Properties

Abstract Electronic and optical properties of graphene oxide (GO), under an external electric field (Eext) applied in three directions of space (x, y, z), are investigated using the density functional theory (DFT). The application of the Eext, causes a significant modifications to the electronic and optical properties of GO material. It has change the band gap, total density of states (TDOS), partial density of states (PDOS), absorption coefficient (α), dielectric function, optical conductivity, refractive index and loss function. The band gap of GO layer increases under the effects of the Eext, applied in x and y directions. On the other hand, for z direction, the band gap decreases by the effects of the Eext. The peaks of the TDOS around the Fermi level, change by the Eext applied in (x, y, z) directions. The α peaks of the GO sheet, decreases by the Eext applied in x direction, and increases if Eext applied in y and z directions. It is found that, the electronic and optical properties of GO layer, could be affected by the effects of the Eext and by its direction of application.

scholarly journals Hydrolysis Mechanism of Bismuth in Chlorine Salt System Calculated by Density Functional Method

2020 ◽  
Vol 71 (6) ◽  
pp. 178-193
Author(s):  
Liao Chunfa ◽  
Xu Zhenxin ◽  
Zou Jianbai ◽  
Jiang Pinguoo
Keyword(s):  
Density Of States ◽  
Density Functional ◽  
Energy Gap ◽  
Density Functional Method ◽  
Covalent Bond ◽  
Salt System ◽  
Hydroxyl Group ◽  
Partial Density ◽  
Hydroxyl Groups ◽  
Total Density

Based on the density functional theory, this paper presents the calculated cellular electronic properties of BiCl3, BiOCl and Bi3O4Cl, including unit cell energy, band structure, total density of states, partial density of states, Mulliken population, overlapping population, etc. Combined with the thermodynamic analysis of Bi3+ hydrolysis process in chlorine salt system, the conversion mechanism of oxychloride bond in BiCl3 to form BiOCl and Bi3O4Cl by hydrolysis, ethanololysis and ethylene glycol alcohololysis was obtained by infrared spectroscopy. The results indicate that the energy of Bi3O4Cl cell system was lower than that of BiOCl cell, indicating that the structure of Bi3O4Cl was more stable. From the analysis of bond fluctuation, the electron nonlocality in BiOCl belt was relatively large, and the orbital expansibility was strong; thus the structure of BiOCl was relatively active. The state density map of Bi3O4Cl had the widest energy gap, i.e., the covalent bond between Bi3O4Cl was stronger than BiOCl. Therefore, the hydrolysis of BiCl3 would preferentially generate Bi3O4Cl with a more stable structure. The number of charge arrangement, overlapping population and infrared spectrogram indicate that there were two basic ways in the hydrolysis and alcoholysis of BiCl3. Firstly, two chlorine atoms in BiCl3 were replaced by hydroxyl groups ionized by water and alcohol to form [Bi(OH)2Cl] monomer, and BiOCl and Bi3O4Cl were formed by intra-molecular dehydration or inter-molecular dehydration. The other way was that the Bi atom directly reacted with the OH ionized by water and alcohol to form the [Bi-OH] monomer, and the Cl atom replaced the H atom on the hydroxyl group in the [Bi-OH] monomer to further form BiOCl and Bi3O4Cl.

scholarly journals Electronic Transitions, Inter- and Intra-Bond Interactions of an Azabicycle Single Crystal using DFT

2021 ◽  
Vol 33 (10) ◽  
pp. 2365-2372
Author(s):  
J. Dineshkumar ◽  
S. Subashchandrabose ◽  
S. Niaz ◽  
P. Parthiban
Keyword(s):  
Functional Groups ◽  
Density Of States ◽  
Electronic Transitions ◽  
Partial Density ◽  
Electronic Charge ◽  
Total Density ◽  
X Ray Diffraction ◽  
Mannich Condensation ◽  
Td Dft ◽  
Total Density Of States

2,4-Diphenyl-3-azabicyclo[3.3.1]nonan-9-one O-benzyloxime (ABN-OBn) was synthesized by modified Mannich condensation, purified by recrystallization and single crystals were grown by slow evaporation from ethanol. The empirical formula of the molecule is C27H28N2O as witnessed by HRMS, elemental analysis and the X-ray diffraction. The crystal belongs to triclinic system (α = 73.640, β = 78.505, γ = 87.078) with P-1 space group. The electronic excited states of ABN-OBn have been calculated using TD-DFT/B3LYP/6-31G(d,p) level of theory, in order to investigate the electronic transitions within the molecule. Frontier molecular orbitals (FMOs) of ABN-OBn have been studied to understand the electronic charge distributions and its band gap (5.0514 eV/245.45 nm). Density of states (DOS), partial density of states (PDOS) and total density of states (TDOS) with respect to functional groups were computed to investigate the electron densities of functional groups in the molecule. Natural bond orbital (NBO) has been performed to explore the intramolecular π-π* interaction of the compound.

scholarly journals Ultra-wide bandgap semiconductor behavior of NaCaF3 fluoro-perovskite with external static isotropic pressure and its impact on optical properties: First-principles computation

2021 ◽  
Author(s):  
Syed Sajid Ali Gillani ◽  
Nisar Fatima ◽  
M. Shakil ◽  
R. Kiran ◽  
M. B. Tahir ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Density Of States ◽  
Density Functional ◽  
External Pressure ◽  
Partial Density ◽  
Total Density ◽  
Isotropic Pressure ◽  
The Impact

Abstract A comprehensive theoretical study to investigate the outcomes of externally applied static isotropic pressure (0 GPa - 50 GPa) on electronic, optical and structural properties of NaCaF3, using density functional theory (DFT) based CASTEP (Cambridge Serial Total Energy Package) code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA), is reported. The electronic bandgap shows the increasing trend 4.773 eV - 6.203 eV (direct bandgap) with increasing external pressure. The increase in bandgap is significant up to 20 GPa as compared to higher external pressures. The mystery of increasing band gap is nicely decoded by total density of states (TDOS) and elemental partial density of states (EPDOS). Optical properties have been calculated to analyze the impact of increment in band gap on them. We observed that highest peak of energy loss function L(w) shows the blue shift which confirms the increment of band gap. At zero photon energy, for 0 GPa, the static refractive index n(w) has value of 1.4456. After applying external pressure, there is a slight increase in n(w) which favors the semiconducting behavior of ternary compound. The energy points at which the absorption peak is maxima, the refractive index has lowest value.

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