First-principles investigation of the electronic band structures and optical properties of quaternary ABaMQ4 (A = Rb, Cs; M = P, V; and Q = S) metal chalcogenides

2018 ◽  
Vol 32 (30) ◽  
pp. 1850337
Author(s):  
Shahid Ullah ◽  
Hayat Ullah ◽  
Abdullah Yar ◽  
Sikander Azam ◽  
A. Laref
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Charge ◽  
Electromagnetic Spectrum ◽  
Metal Chalcogenides ◽  
Electronic Band ◽  
Charge Densities ◽  
Electronic Band Structures

In this paper, we study the optoelectronic properties of quaternary metal chalcogenide semiconductor ABaMQ4 (A = Rb, Cs; M = P, V; and Q = S) compounds using state-of-the-art density functional theory (DFT) with TB-mBJ approximation for the treatment of exchange-correlation energy. In particular, the electronic and optical properties of the relaxed geometries of these compounds are investigated. Our first-principles ab-initio calculations show that the CsBaPS4 and RbBaPS4 compounds have direct bandgaps whereas the CsBaVS4 compound exhibits indirect bandgap nature. Importantly, the theoretically calculated values of the bandgaps of the compounds are consistent with experiment. Furthermore, our analysis of the electronic charge densities of these compounds indicates that the above quaternary chalcogenides have mixed covalent and ionic bonding characters. The effective masses of these compounds are also calculated which provide very useful information about the band structure and transport characteristics of the investigated compounds. Similarly, high absorptivity in the visible and ultraviolet regions of the electromagnetic spectrum possibly predicts and indicates the importance of these materials for potential optoelectronic applications in this range.

Systematic first principles calculations of the effects of stacking faults defects on the 4H-SiC band structure

2010 ◽  
Vol 1246 ◽  
Author(s):  
Massimo Camarda ◽  
pietro delugas ◽  
Andrea Canino ◽  
Andrea Severino ◽  
nicolo piluso ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Stacking Faults ◽  
Perfect Crystal ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Functional Theory ◽  
Experimental Findings ◽  
Electronic Band Structures ◽  
Formation Energies

AbstractShockley-type Stacking faults (SSF) in hexagonal Silicon Carbide polytypes have received considerable attention in recent years since it has been found that these defects are responsible for the degradation of forward I-V characteristics in p-i-n diodes. In order to extend the knowledge on these kind of defects and theoretically support experimental findings (specifically, photoluminescence spectral analysis), we have determined the Kohn-Sham electronic band structures, along the closed path Γ-M-K-Γ, using density functional theory. We have also determined the energies of the SSFs with respect to the perfect crystal finding that the (35) and (44) SSFs have unexpectedly low formation energies, for this reason we could expect these two defects to be easily generated/expanded either during the growth or post-growth process steps.

Electronic band structures of Ge1−xSnx semiconductors: A first-principles density functional theory study

2013 ◽  
Vol 113 (6) ◽  
pp. 063517 ◽  
Author(s):  
Ming-Hsien Lee ◽  
Po-Liang Liu ◽  
Yung-An Hong ◽  
Yen-Ting Chou ◽  
Jia-Yang Hong ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Band Structures ◽  
Electronic Band ◽  
Functional Theory ◽  
Electronic Band Structures

STRUCTURAL, ELECTRONIC, MAGNETIC AND OPTICAL PROPERTIES OF FERROMAGNETIC Pb1-xEuxSe AND Pb1-xEuxTe ALLOYS (x = 0, 0.25, 0.50, 0.75 AND 1)

2013 ◽  
Vol 27 (19) ◽  
pp. 1350100 ◽  
Author(s):  
S. M. ALAY-E-ABBAS ◽  
S. YOUNAS ◽  
S. HANIF ◽  
M. SHARIF ◽  
IQBAL HUSSAIN ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Full Potential ◽  
Nonlinear Behaviour ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Plane Wave Method ◽  
Energy Dependent ◽  
Electronic Band Structures

First-principles total energy calculations have been performed using full potential linear-augmented-plane-wave method within the framework of density functional theory to study the structural, electronic, magnetic and optical properties of the Pb 1-x Eu x Se and Pb 1-x Eu x Te (0 ≤ x ≤1) alloys in the ferromagnetic (FM) ordering. The calculations have been extended to treat the strongly localized f electrons of Eu atom by the self-interaction correction (SIC) approach. For structural optimization, the Wu and Cohen generalized gradient approximation (GGA) functional has been used, whereas for calculating electronic properties, the GGA parameterization scheme formulated by Engel and Vosko (EV) has also been utilized. It has been observed that the use of experimental value of Coulomb parameter (Uf- expt. ) within the SIC does not yield an accurate EuSe and EuTe energy band structure. The improvement in the electronic band structures of nonmagnetic PbSe / PbTe and ferromagnetic EuSe / EuTe have been achieved by considering the effects of spin–orbit coupling for Pb atoms, by a suitable choice of U and by treating the U values for Eu atom's f and d electrons as parameters. The electronic and optical properties of FM Pb 1-x Eu x Se in agreement with experiments can be achieved by combining EV GGA with a Hubbard U < Uf- expt. , however, a stronger and stable AFM coupling in EuTe leaves the above scheme unable to provide good electronic structure of FM Pb 1-x Eu x Te . In case of Pb 1-x Eu x Se the nonlinear behaviour of electronic structure is reflected in the optical properties of Eu -doped PbSe that have been studied in terms of incident photons' energy dependent complex dielectric function.

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.

scholarly journals Electronic Structure, Electronic Charge Density, and Optical Properties Analysis of GdX3 (X = In, Sn, Tl, and Pb) Compounds: DFT Calculations

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jisha Annie Abraham ◽  
Gitanjali Pagare ◽  
Sankar P. Sanyal
Keyword(s):  
Optical Properties ◽  
Charge Density ◽  
Density Of States ◽  
Density Functional ◽  
Electronic Charge ◽  
Ambient Conditions ◽  
Electronic Charge Density ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Calculated Density

The electronic properties of magnetic cubic AuCu3 type GdX3 (X = In, Sn, Tl, and Pb) have been studied using first principles calculations based on density functional theory. Because of the presence of strong on-site Coulomb repulsion between the highly localized 4f electrons of Gd atoms, we have used LSDA + U approach to get accurate results in the present study. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The calculated density of states at the Fermi level N(EF) shows good agreement with the available experimental results. The calculated electronic charge density plots show the presence of ionic bonding in all the compounds along with partial covalent bonding except in GdIn3. The complex optical dielectric function’s dispersion and the related optical properties such as refractive indices, reflectivity, and energy-loss function were calculated and discussed in detail.

Effects of Si Doping on the Structural, Electronic and Optical Properties of Barium Chalcogenide BaS: A First-Principles Study

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050014
Author(s):  
H. Absike ◽  
H. Labrim ◽  
B. Hartiti ◽  
H. Ez-Zahraouy
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Original Structure ◽  
Functional Theory ◽  
Electron Charge Density ◽  
Electronic And Optical Properties ◽  
Charge Densities ◽  
The Density Functional Theory ◽  
Si Doped

In this work, the structural, electronic and optical properties of Si-doped barium chalcogenide [barium sulfide (BaS)] with different Si concentrations ([Formula: see text]) are investigated by the first-principles calculations based on the density functional theory (DFT). The band structures, charge densities and complex dielectric functions of the pure as well as Si-doped BaS were presented and analyzed in detail using TB-mBJ approach by WIEN2k package. It is found that silicon concentration can control the bandgap by reducing it to values around 1.4[Formula: see text]eV and 1.6[Formula: see text]eV for 12.5% and 6.25% of Si-doped BaS, respectively. The electron charge density indicates the ionic bonding between silicon and sulfur atoms due to the high electronegativity between them. In fact, the results show that the absorption peaks of Si-doped BaS are enhanced compared with pure BaS. These results suggest that the Ba[Formula: see text]SixS original structure displays excellent physical properties thereby revealing that it is a promising material in advanced optoelectronic and solar cell applications.

Electronic and optical properties of pentagonal-B2C monolayer: A first-principles calculation

2017 ◽  
Vol 31 (08) ◽  
pp. 1750044 ◽  
Author(s):  
Mosayeb Naseri ◽  
Jafar Jalilian ◽  
A. H. Reshak
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Valence Band Maximum ◽  
First Principles Calculation ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Energy Consideration ◽  
Normal Light

The electronic and optical properties of pentagonal B2C (penta-B2C) monolayer are investigated by means of the first-principles calculations in the framework of the density functional theory. The cohesive energy consideration confirms the good stability of the B2C nanostructure in this phase. The electronic band structure reveals that the valence band maximum (VBM) is located at [Formula: see text]-point of the first Brillouin zone (BZ) whereas the conduction band minimum (CBM) is situated at the center of the BZ, resulting in an indirect energy bandgap of about 1.5 eV. Furthermore, a calculated low absorption and low reflection of the material in low energy ranges denote the transparency of the B2C monolayer in the investigated range for normal light incidence. The obtained results may find application in fabrication of future opto-electronic devices.

Prediction of half-metallicity in the NaS, NaSe and NaTe alkali-metal chalcogenides using first principles

2018 ◽  
Vol 07 (03) ◽  
pp. 1850015 ◽  
Author(s):  
H. Sadouki ◽  
A. Belkadi ◽  
Y. Zaoui ◽  
S. Amari ◽  
K. O. Obodo ◽  
...  
Keyword(s):  
Alkali Metal ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Data ◽  
Stable Phase ◽  
Full Potential ◽  
Metal Chalcogenides ◽  
Electronic Band ◽  
Half Metallic ◽  
Binary Compounds

First-principles full-potential linearized augmented plane-wave method based on density functional theory is used to investigate the structural, electronic and magnetic properties of NaS, NaSe and NaTe alkali-metal chalcogenides binary compounds. These compounds in different crystalline phases: NaCl (B1), CsCl (B2), ZB (B3), NiAs (B81), WZ (B4) and Pnma were calculated within the generalized gradient approximation (GGA-PBE) and the modified Becke–Johnson approach (mBJ-GGA-PBE) for the exchange-correlation energy and potential. We found that the most stable phase for the NaX binary compounds is the nonmagnetic Pnma phase. The calculated lattice parameters, bulk moduli, their first-pressure derivatives and internal parameters are in good agreement with the other theoretical data. The electronic band structure and density of states show that half-metallic and magnetic character arises, which can be attributed to the presence of spin-polarized [Formula: see text] orbitals in the group VI elements. The NaS, NaSe and NaTe binary compounds show half-metallic character in ZB and WZ phases, with an integer magnetic moment of 1 [Formula: see text] per formula unit and half-metallic gaps.

Structural, Electronic and Optical Properties of High (γ)-Li2BeSiO4: First-Principles Calculations

2011 ◽  
Vol 197-198 ◽  
pp. 567-570
Author(s):  
Qi Jun Liu ◽  
Zheng Tang Liu ◽  
Li Ping Feng ◽  
Hao Tian
Keyword(s):  
Optical Properties ◽  
Chemical Bonding ◽  
First Principles ◽  
Density Functional ◽  
Structural Parameters ◽  
Population Analysis ◽  
Functional Theory ◽  
Charge Densities ◽  
Bonding Properties ◽  
Direct Band

We have performed ab-initio total energy calculations using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT) to study structural parameters, electronic structure, chemical bonding and optical properties of orthorhombic Li2BeSiO4. The calculated lattice parameters are in agreement with experimental data. The band structure shows a direct band gap. From the DOS analysis, charge densities and population analysis, electronic and chemical bonding properties have been studied. Furthermore, in order to understand the mechanism of optical transitions of orthorhombic Li2BeSiO4, the complex dielectric functions are calculated and analysed.

First-principles calculations of optoelectronic properties of CaO: Eu+2 (SrO: Eu+2) for energy applications

2018 ◽  
Vol 32 (30) ◽  
pp. 1850333 ◽  
Author(s):  
Sikander Azam ◽  
Zeesham Abbas ◽  
Banat Gul ◽  
M. Shoaib Khan ◽  
Muhammad Irfan ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Energy Gap ◽  
Uniaxial Anisotropy ◽  
Spectral Structure ◽  
Electronic Band ◽  
Covalent Bonds ◽  
Substantial Impact ◽  
Energy Bandgap

We have performed the first-principles density functional theory (DFT) and DFT[Formula: see text]U calculations on the electronic and optical properties of CaO: Eu[Formula: see text] (SrO: Eu[Formula: see text]) phosphors compounds. Herein, we have focused on the polarization of the electronic structures, i.e., the energy bandgap and the density of states. All electrons were treated within the most common exchange and correlation functional called generalized gradient approximation plus optimized effective Hubbard parameter U as GGA[Formula: see text]U. GGA[Formula: see text]U is a very effective tool for describing the electronic band energy upto considerable accuracy. Hence, we have opted for the arbitrary values of U as 3.0, 4.0, 5.0 and 7.0 eV to treat the strongly correlated electrons for obtaining the matching result with the experimental one. However, GGA[Formula: see text]U is highly expensive in terms of computation due to interaction of d or f electrons. The result shows that the appearance of Eu-4f states at the valance band maximum of the spin-up causes a substantial impact on the electronic properties of the studied compounds. The value of energy bandgap is smaller in case of spin up as compared to spin down case. In case of majority spin, the energy gap of 2.224 (2.14) eV belongs to the Eu-4f orbitals and governs the CBM. The partial densities of states (PDOS) structure displays a strong hybridization that may be pointed to the formation of covalent bonds. The calculated and the measured values are in good agreement with each other. In the study of optical properties of the compound, the optical spectral structure shows a lossless region and uniaxial anisotropy. The value of uniaxial anisotropy is positive at static limit and its value is negative above this value.

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