scholarly journals Estimation of Lattice Constants and Band Gaps of Group-III Nitrides using Local and Semi Local Functionals

2018 ◽  
Vol 34 (4) ◽  
pp. 2137-2143 ◽  
Author(s):  
Sandeep Arora ◽  
Dharamvir Singh Ahlawat ◽  
Dharambir Singh
Keyword(s):  
Band Gap ◽  
Local Density ◽  
Group Iii Nitrides ◽  
Lattice Parameters ◽  
Exchange Potential ◽  
Generalized Gradient ◽  
Group Iii ◽  
Lattice Constants ◽  
Mean Error ◽  
Gap Values

We performed the optimization of lattice constants of Group- III nitrides (InN, AlN, GaN) in wurtzite and Zinc blende structures using various semilocal exchange correlation functional in generalized gradient approximations (GGA) namely PBE, WC, PBEsol in addition to local density approximation (LDA) functional. We used these optimized lattice parameters to predict the band gap values using modified Becke Johnson exchange potential with original and improved parameterization as suggested by David Koller for semiconductors having band gap values below 7eV. Among the different functionals considered, PBEsol optimize the lattice parameters with smallest mean error (0.00639 Å) relative to experimental values, while WC approximation with a slightly greater value of mean error (0.00513 Å). It is shown that mBJLDA approximation improves the band gap for the materials studied when compared with LDA and GGA results. It is also shown that LDA optimized parameters with mBJLDA approximation, which leads to mean error of 0.162 eV reproduces the experimental band gap in most efficient way.

Ab intio Investigations of Lattice Parameters in ZnMgO Alloys

2009 ◽  
Vol 1201 ◽  
Author(s):  
Markus Heinemann ◽  
Marcel Giar ◽  
Christian Heiliger
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Calculations ◽  
Lattice Parameters ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Lattice Constants ◽  
Exchange Correlation ◽  
Vegard’S Law ◽  
Constant Unit

AbstractWe perform density functional theory calculations to determine equilibrium lattice parameters of wurtzite Zn1-xMgxO alloys for Mg concentrations x ranging from 0 to 31.25 %. We use the local density approximation (LDA) as well as the generalized gradient approximation (GGA) for the exchange correlation functional. For the lattice constants a and c we find a deviation from Vegard's law and a constant unit cell volume independent of the Mg concentration.

Laplacian free and asymptotic corrected semilocal exchange potential applied to the band gap of solids

2019 ◽  
Vol 21 (35) ◽  
pp. 19639-19650 ◽  
Author(s):  
Abhilash Patra ◽  
Subrata Jana ◽  
Hemanadhan Myneni ◽  
Prasanjit Samal
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Exchange Potential ◽  
Functional Theory ◽  
Type Semiconductor ◽  
Local Density Functional Theory ◽  
Local Density Functional

Improved band gap of n-type semiconductor ZrS2 within semi-local density functional theory is shown. The band gap of mBR-TBMBJ agrees well with the hybrid HSE06 functional.

Structural Electronic and Optical Properties of MgO, CaO and SrO Binary Compounds: Comparison Study

2016 ◽  
Vol 257 ◽  
pp. 123-126 ◽  
Author(s):  
Salima Labidi ◽  
Jazia Zeroual ◽  
Malika Labidi ◽  
Kalthoum Klaa ◽  
Rachid Bensalem
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Alternative Form ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Optical Dielectric Constant ◽  
Reported Data

First-principles calculations for electronic and optical properties under pressure effect of MgO, SrO and CaO compounds in the cubic structure, using a full relativistic version of the full-potential augmented plane-wave (FP-LAPW) method based on density functional theory, within the local density approximation (LDA) and the generalized gradient approximation (GGA), have been reported. Furthermore, band structure calculations have been investigated by the alternative form of GGA proposed by Engel and Vosko (GGA-EV) and modified by Becke-Johnson exchange correlation potential (MBJ-GGA). All calculated equilibrium lattices, bulk modulus and band gap at zero pressure are find in good agreement with the available reported data. The pressure dependence of band gap and the static optical dielectric constant are also investigated in this work.

scholarly journals Extreme pressure conditions of bas based materials: Detailed study of structural changes, band gap engineering, elastic constants and mechanical properties

2019 ◽  
Vol 13 (4) ◽  
pp. 401-410
Author(s):  
Dejan Zagorac ◽  
Jelena Zagorac ◽  
Klaus Doll ◽  
Maria Cebela ◽  
Branko Matovic
Keyword(s):  
Mechanical Properties ◽  
Band Gap ◽  
Elastic Constants ◽  
Density Functional ◽  
Structural Changes ◽  
High Pressures ◽  
Local Density ◽  
Structure Property ◽  
Generalized Gradient ◽  
Band Gap Engineering

A Density Functional Theory (DFT) study has been performed in order to investigate behaviour of barium sulfide (BaS) at high pressures, and relationship between computed properties, in great detail. Novel predicted and previously synthesized BaS modifications have been calculated using Local Density Approximations (LDA) and Generalized Gradient Approximation (GGA) functionals. In particular, a detailed investigation of structural changes and its corresponding volume effect up to 100GPa, with gradual pressure increase, has been performed from the first principles. Band gap engineering of the experimentally observed BaS phases at high pressures has been simulated and structure-property relationship is investigated. For each of the predicted and experimentally observed BaS structures, elastic constants and mechanical properties under compression have been investigated (e.g. ductility/brittleness, hardness, anisotropy). This study offers a new perspective of barium sulphide as a high pressure material with application in ceramics, optical and electrical technologies.

First-Principles Study of Structural, Electronic, Optical and Elastic Properties of Cadmium Based Fluoro-Perovskite MCdF3 (M= Rb, Tl)

2019 ◽  
Vol 297 ◽  
pp. 173-186 ◽  
Author(s):  
Abderrahmane Cheriet ◽  
Brahim Lagoun ◽  
Mohamed Halit ◽  
Mourad Zaabat ◽  
Chadli Abdelhakim ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Local Density ◽  
Poisson Ratio ◽  
Exchange Potential ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Conduction Bands

This paper presents a theoretical study using the full potential linearized augmented plane wave approach (FP-LAPW) based on the density functional theory (DFT) to predict the structural and electronic properties of RbCdF3 and TlCdF3 compounds. The exchange-correlation potential is treated by the local density approximation (LDA), generalized gradient approximation (GGA) and modified Beck-Johnson exchange potential (mBJ). The calculated structural properties such as the equilibrium lattice parameter, the bulk modulus and its pressure derivative are in good agreement with the available data. The obtained results for the band structure and the density of states (DOS) show that the RbCdF3 (TlCdF3) compound have an indirect band gap of 6.77 and 3.07 eV (5.70 and 3.66 eV) with TB-mBJ and WC method respectively. From the electronic transition from valence conduction bands to conduction bands the optical properties were calculated. The elastic constants were calculated using the energy deformation relationship, from these constants the other mechanical properties such as bulk modulus, shear modulus, Young modulus and Poisson ratio were calculate and comment. Lastly, the elastic anisotropy was discussed.

First-principles calculations of structural, electronic, magnetic, elastic and optical properties of tetragonal zircon-type CeVO4

2018 ◽  
Vol 32 (22) ◽  
pp. 1850239
Author(s):  
Wen-Qi Chen ◽  
Hao Wang ◽  
Yi Mu ◽  
Cui-E Hu ◽  
Yan Cheng
Keyword(s):  
Optical Properties ◽  
Magnetic Moment ◽  
Ground State ◽  
Local Density ◽  
Coulomb Repulsion ◽  
Lattice Parameters ◽  
Experimental Result ◽  
Generalized Gradient ◽  
Magnetic Ground State ◽  
Zircon Type

We have performed comprehensive first-principle calculations to investigate the structural, electronic, magnetic, elastic and optical properties of the tetragonal zircon-type CeVO4. The local density approximation plus U (LDA+U) and generalized gradient approximation plus U (GGA+U) methods are used to interpret the strong Coulomb repulsion among the localized Ce 4f electrons. Without the effective U parameters, the obtained ground state of the ferromagnetic (FM) metal is not consistent with the experimental result. However, we can get the antiferromagnetic (AFM2: the magnetic ground state) insulating ground state for CeVO4 by LDA+U and GGA+U. It reveals that the result is in agreement with the experiment. For AFM2 CeVO4, the dependence of properties on the U parameters has been studied in detail. The effect of spin–orbit coupling (SOC) has also been investigated in detail. The demonstrated properties include volume, lattice parameters, bandgap, the density of states (DOS) and spin magnetic moment of Ce atom. With the Hubbard U parameter around 6 eV, the lattice parameters (a=7.396 Å, V=351.82 Å3, c/a=0.874), bulk modulus B0 (121 GPa), insulating gap (2.157 eV) and magnetic moment (0.97 [Formula: see text] per Ce atom) are consistent with the experiments and other theoretical results. Besides, the elasticity-related properties and optical properties have also been calculated for U=0,2,4 and 6 eV.

BULK MODULUS CALCULATIONS FOR GROUP-IV CARBIDES AND GROUP-III NITRIDES

2004 ◽  
Vol 18 (24) ◽  
pp. 1247-1254 ◽  
Author(s):  
A. MAHMOOD ◽  
L. E. SANSORES ◽  
J. HEIRAS
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Group Iv ◽  
Hard Coatings ◽  
Generalized Gradient ◽  
Group Iii ◽  
Quantum Mechanical Method

Wide band gap semiconductors such as group-IV carbides ( SiC , GeC ) and group-III nitrides ( AlN , GaN and BN ) are known to be important materials for novel semiconductor applications. They also have interesting mechanical properties such as having a particularly high value for their bulk modulus and are therefore potential candidates for hard coatings. In this paper we report the theoretical calculations for the bulk modulus for zincblende and wurzite polytypes of these materials. The Density Functional and Total-energy Pseudopotential Techniques in the Generalized Gradient approximation, an ab initio quantum mechanical method, is used to obtain the theoretical structure, from which equilibrium lattice parameters and volume of the cell versus pressure may be extracted. The Murnaghan's equation of state is then used to calculate bulk modulus under elastic deformation, which is related to the hardness of a material under certain conditions. The results for bulk modulus are compared with other theoretical and experimental values reported in the literature.

Structural and electronic properties of zincblende phase of TlxGa1−x AsyP1−y quaternary alloys: First-principles study

Open Physics ◽  
2013 ◽  
Vol 11 (12) ◽  
Author(s):  
Sinem Gulebaglan ◽  
Emel Dogan ◽  
Murat Aycibin ◽  
Mehmet Secuk ◽  
Bahattin Erdinc ◽  
...  
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Local Density ◽  
Density Approximation ◽  
Quaternary Alloys ◽  
Lattice Constants ◽  
Vegard’S Law ◽  
Structural And Electronic Properties

AbstractUsing the first-principles band-structure method, we have calculated the structural and electronic properties of zincblende TlAs, TlP, GaAs and GaP compounds and their new semiconductor TlxGa1−x AsyP1−y quaternary alloys. Structural properties of these semiconductors are obtained with the Perdew and Wang local-density approximation. The lattice constants of TlxGa1−x As, TlxGa1−x P ternary and TlxGa1−x AsyP1−y quaternary alloys were composed by Vegard’s law. Our investigation on the effect of the doping (Thallium and Arsenic) on lattice constants and band gap shows a non-linear dependence for TlxGa1−x AsyP1−y quaternary alloys. The band gap of TlxGa1−x AsyP1−y , E g(x, y) concerned by the compositions x and y. To our awareness, there is no theoretical survey on TlxGa1−x AsyP1−y quaternary alloys and needs experimental verification.

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