scholarly journals Investigations on Cmc21-Si2P2X structures and physical properties by first-principles calculations

2021 ◽  
Vol 24 (4) ◽  
pp. 43602
Author(s):  
R. Yang ◽  
X. Gao ◽  
F. Wu ◽  
Q. Wei ◽  
M. Xue
Keyword(s):  
Optical Properties ◽  
Sound Velocity ◽  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Elastic Stability ◽  
First Principles Calculations ◽  
Shear Moduli ◽  
Longitudinal Sound Velocity ◽  
Bandgap Semiconductors

The new structures, Cmc21-Si2P2X (X=S, Se, Te, and Po), are predicted, and their mechanical, electronic and optical properties are investigated with the density functional theory, by first principles calculations. The elastic constants of the four compounds are calculated by the stress-strain method. The calculations of the elastic stability criteria and phonon dispersion spectra imply that they are mechanically and dynamically stable at zero pressure. The mechanical parameters, such as shear moduli G, bulk moduli B, Young's moduli E and Poisson's ratios v are evaluated by the Voigt-Reuss-Hill approach. The Cmc21-Si2P2X has the largest hardness due to the largest Young's modulus in the four compounds, and it is a covalent crystal. The anisotropies of their mechanical properties are also analyzed. The band structures and densities of states, which are calculated by using HSE06, show that Cmc21-Si2P2X compounds are indirect bandgap semiconductors, and the values of the band gaps decrease with increasing atomic number from S, Se, Te, to Po. In addition, the longitudinal sound velocity and transverse sound velocity for Cmc21-Si2P2X have been investigated. The dielectric constant, electron energy loss, refractive index, reflectivity, absorption and conductivity are analyzed to gain the optical properties of Si2P2X.

First Principles Calculations of Electronic Structure and Optical Properties of Cu-Doped SnS2

2013 ◽  
Vol 373-375 ◽  
pp. 1965-1969
Author(s):  
Kun Nan Qin ◽  
Ling Zhi Zhao ◽  
Yong Mei Liu ◽  
Fang Fang Li ◽  
Chao Yang Cui
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Optical Absorption Coefficient ◽  
Impurity Level ◽  
First Principles Calculations ◽  
Absorption Region ◽  
Functional Theory ◽  
The Density Functional Theory

The electronic structure and optical properties of Cu-doped SnS2with Sn-substituted content of 0, 12.5 and 37.5 at.% were successfully calculated by the first principles plane-wave pseudopotentials based on the density functional theory. It is found that the intermediate belts appear near the Fermi level and the energy band gap becomes narrower after the doping of the Cu atoms. The absorption peaks show a remarkable redshift and the absorption region broadens relatively after introducing acceptor impurity level. When Sn atoms of 37.5 at% were substituted by Cu, the optical absorption coefficient is significantly improved in the frequency range below 5.58 eV and over 8.13 eV.

Electronic Structure, Effective Masses and Optical Properties of Monoclinic HfO2 from First-Principles Calculations

2011 ◽  
Vol 216 ◽  
pp. 341-344 ◽  
Author(s):  
Qi Jun Liu ◽  
Zheng Tang Liu ◽  
Li Ping Feng
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Effective Masses ◽  
Indirect Band Gap ◽  
Calculated Equilibrium

Electronic structure, effective masses and optical properties of monoclinic HfO2were studied using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT). The calculated equilibrium lattice parameters are in agreement with the previous works. From the band structure, the effective masses and optical properties are obtained. The calculated band structure shows that monoclinic HfO2has indirect band gap and all of the effective masses of electrons and holes are less than that of a free electron. The peaks position distributions of imaginary parts of the complex dielectric function have been explained according to the theory of crystal-field and molecular-orbital bonding.

First-principles study on the structural, elastic and electronic properties of the four Si3Sb4 compounds

2019 ◽  
Vol 33 (05) ◽  
pp. 1950047
Author(s):  
Ruike Yang ◽  
Bao Chai ◽  
Qun Wei ◽  
Minhua Xue ◽  
Ye Zhou
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Elastic Anisotropy ◽  
Functional Theory ◽  
Shear Moduli ◽  
Young’S Moduli ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

For novel [Formula: see text]-Si3Sb4, pseudocubic-Si3Sb4, cubic-Si3Sb4 and [Formula: see text]-Si3Sb4, the structural, elastic and electronic properties are investigated using first-principles density functional theory (DFT). The elastic constants and phonon dispersion spectra show that they are mechanically and dynamically stable. The bulk moduli, shear moduli, Young’s moduli, Poisson’s ratios and Pugh ratios for the four compounds have been calculated. The bulk moduli indicate that the bond strength of [Formula: see text]-Si3Sb4 is stronger than others. The values of the Poisson’s ratios and Pugh ratios show that pseudocubic-Si3Sb4 is the stiffest among the four Si3Sb4 compounds. Tetragonal Si3Sb4 are more brittle than cubic Si3Sb4. For the four Si3Sb4 compounds, the elastic anisotropies are analyzed via the anisotropic indexes and the 3D surface constructions. The [Formula: see text]-Si3Sb4 elastic anisotropy is stronger than others and the [Formula: see text]-Si3Sb4 is weaker than others. The calculated band structures show that they exhibit metallic features. The results of their TDOS show that there are many similarities. The peaks of TDOS are derived from the contributions of Si “s”, Si “p”, Sb “s” and Sb “p” states.

First-principles calculations to investigate structural, electronic and optical properties of (ZnSe)n/(ZnTe)n superlattices

2020 ◽  
Author(s):  
Messaoud Caid
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Full Potential ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Lmto Method ◽  
Binary Compounds

An investigation into the structural, electronic and optical properties of superlattices(SLs) (ZnSe)n/(ZnTe)n was conducted using first principles calculations based on density functional theory (DFT). The total energies were calculated within the full-potential linear muffin-tin orbital (FP-LMTO) method augmented by a plane-wave basis (PLW), implemented in LmtART 7.0 code. The effects of the approximations to the exchange-correlation energy were treated by the local density approximation (LDA). The ground state properties of (ZnSe)n/(ZnTe)n binary compounds are determined and compared with the available data. It is found that the superlattice (n-n: 1-1, 2-2 and 3-3) band gaps vary depending on the layers used. The optical constants, including the dielectric function ε(w), the refractive index n(w) and the reflectivity R(w), are calculated for radiation energies up to 35eV.

Investigation of optical properties of Zn1-xVxO (x = 0.0, 0.125, 0.25, 0.5) by first principles calculations

2014 ◽  
Vol 28 (31) ◽  
pp. 1450243
Author(s):  
R. Taghavi Mendi ◽  
S. M. Elahi ◽  
M. R. Abolhassani
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Dielectric Function ◽  
First Principles ◽  
Density Functional ◽  
Full Potential ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Electron Model ◽  
Low Energies

In this paper, some optical properties of Zn 1-x V x O (0 ≤ x ≤ 0.5) such as real and imaginary part of dielectric function, energy loss function, plasmon energies and refractive index are investigated by first principles calculations. The calculations were performed in density functional theory (DFT) framework using full potential linear augmented plane wave (FP-LAPW) and generalized gradient approximation (GGA). Analysis of dielectric function shows that by substituting V instead of Zn in Zn 1-x V x O , static dielectric function, absorption and anisotropy at low energies are increased. The investigations show that V doping in ZnO affects plasmon energies. The plasmon energies have been compared with free electron model. The calculated plasmon energy for pure ZnO is nearly close to other works. The refractive index at low energies is increased significantly, so that V -doped ZnO can be used as a high refractive material.

scholarly journals First-principles calculations of LiNbO3 optical properties: From far-infrared to ultraviolet

2018 ◽  
Vol 32 (05) ◽  
pp. 1850063 ◽  
Author(s):  
Vladimir Saleev ◽  
Alexandra Shipilova
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Atomic Orbital ◽  
Hybrid Approach ◽  
Far Infrared ◽  
Basis Sets ◽  
Dielectric Tensor ◽  
First Principles Calculations ◽  
Wide Range

We perform first-principles calculations of optical properties for ferroelectric phase of LiNbO3 crystal using density functional theory (DFT) for wide range of wavelengths, from far-infrared (IR) to ultraviolet. We study frequency dependence of complex dielectric tensor and related quantities, such as refractive and reflection indices, absorption coefficients, etc. Our calculation incorporates advantages of numerical approaches based on atomic-orbital all-electron Gaussian-type basis sets, as it is realized in CRYSTAL14 program. We compared predictions obtained in general-gradient approach with PBESOL exchange-correlation functional and in hybrid approach with PBESOL0 functional, and we have found that hybrid PBESOL0 functional is more applicable to describe the wide set of the experimental data.

Properties of Cmc21-X2As2O (X = Si, Ge, and Sn) by First-Principles Calculations

2018 ◽  
Vol 73 (11) ◽  
pp. 1025-1035 ◽  
Author(s):  
Ruike Yang ◽  
Yucan Ma ◽  
Qun Wei ◽  
Dongyun Zhang
Keyword(s):  
Density Functional ◽  
Phonon Dispersion ◽  
Dielectric Constants ◽  
First Principles Calculations ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Narrow Bandgap ◽  
Bandgap Semiconductors ◽  
Mechanical Strengths ◽  
Static Dielectric Constants

AbstractFor the compounds Cmc21-X2As2O (X = Si, Ge, and Sn), the stabilities are verified by the elastic constants and the phonon dispersion spectra. The structural, mechanical, electronic, and optical properties are investigated by using density functional theory (DFT) calculations. For Cmc21-X2As2O, the mechanical strengths in the [100], [010], and [001] directions are studied. Young’s modulus for Cmc21-Ge2As2O is more anisotropic than that of Cmc21-Si2As2O and Cmc21-Sn2As2O. The band structures of Cmc21-Si2As2O and Cmc21-Sn2As2O show that they are indirect-bandgap semiconductors with bandgaps of 2.744 and 2.201 eV, by using the HSE06 hybrid functional. Cmc21-Ge2As2O is a direct narrow-bandgap semiconductor with a bandgap of 2.131 eV. The static dielectric constants of Cmc21-Si2As2O and Cmc21-Sn2As2O in the [001] direction are higher than those in the [100] and [010] directions. The static dielectric constant of Cmc21-Ge2As2O in the [001] direction is lower than those in the [100] and [010] directions.

scholarly journals Electronic and optical properties of Ba(1-x)Ca(x) TiO3 and Ba(1-x)Sr(x)TiO3

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
A. Belaaraj ◽  
O. Tahiri ◽  
S. Kassou ◽  
R. El Mrabet
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Low Energy ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Densities Of States ◽  
Indirect Band Gap

The effect of Ca and Sr-doping on the structural electronic and optical properties of the cubic Ba1-xCaxTiO3 and Ba1-xSrxTiO3 (x=0.4, 0.6) mixed crystals was investigated using first-principles calculations based on density functional theory (DFT). The calculated band structures based on the optimized geometry of the cell for the solid solutions show an indirect band gap character at M-points, with low energy dispersion along height symmetry directions in the Brillouin zone. The band gaps increase with Ca and Sr concentrations. The total and partial densities of states were analyzed to examine the contribution of different orbitals to the maximum of valence band and the minimum of the conduction band. The optical properties such as reflectivity, energy loss, refractive index and extinction coefficient were studied. #DFT_calculations #band_gap #density_of_states #optical_properties

scholarly journals First Principles Study on the Electronic Structure and Optical Properties of La Doped YB6 Crystals

2021 ◽  
pp. X
Author(s):  
Hongbo TANG ◽  
Qiuyue LI ◽  
Jian ZHOU ◽  
Lihua XIAO ◽  
Ping PENG
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Near Infrared ◽  
Infrared Light ◽  
First Principles Calculations ◽  
Functional Theory ◽  
La Doped

Received 03 January 2020; accepted 17 June 2020 We have investigated the optical properties of La (0, 0.125, 0.250) doped YB6 by means of first-principles calculations within the framework of density functional theory. It was found that electronic and optical properties of YB6 crystals varied remarkably when Y atoms were replaced with La atoms. Furthermore, with increasing content of La in YB6 crystals from 12.5 % to 25 % reflectivity and absorption coefficient of near infrared light decreased obviously, while the transmittance was enhanced.

First-principles investigation of the electronic, mechanical, and thermodynamic properties of europium carbide

2015 ◽  
Vol 93 (4) ◽  
pp. 409-412 ◽  
Author(s):  
Wen Huang ◽  
Lijun Yang
Keyword(s):  
Thermodynamic Properties ◽  
Shear Modulus ◽  
Sound Velocity ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Longitudinal Sound Velocity ◽  
Temperature Melting

The electronic, mechanical, and thermodynamic properties of europium carbide (EuC2) are investigated using first-principles density functional theory within the generalized gradient approximation. The calculated elastic constants indicate that EuC2 is mechanically stable. The shear modulus, Young’s modulus, Poisson’s ratio, the bulk modulus – shear modulus ratio, shear anisotropy, and elastic anisotropy are also calculated. Finally, we obtain the Vickers hardness, averaged sound velocity, longitudinal sound velocity, transverse sound velocity, Debye temperature, melting point, and thermal conductivity of EuC2.

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