Electronic properties of GaN at high-pressure from local density and generalized gradient approximations

2006 ◽  
Vol 37 (4) ◽  
pp. 613-617 ◽  
Author(s):  
S. Saib ◽  
N. Bouarissa
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
Local Density ◽  
Generalized Gradient

scholarly journals High Pressure Study of Structural and Electronic Properties of PbSe

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
P. Bhambhani ◽  
K. Kabra ◽  
B. K. Sharma ◽  
G. Sharma
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
Energy Gap ◽  
Electronic Band Structure ◽  
Local Density ◽  
Structural Phase ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Structural And Electronic Properties ◽  
Direct Band

High pressure structural phase transition and electronic properties have been investigated using the linear combination of atomic orbitals (LCAO) method with two exchange-correlation approximations, the generalized gradient approximation (GGA) and local density approximation (LDA). The present study shows phase transitions from B1 to B27 and B27 to B2 at 6.24 GPa and 16.39 GPa, respectively. Lattice constant, bulk modulus, and energy gap of pressure-induced PbSe are found to be in good agreement with previous theoretical and experimental results. Variation of electronic band structure with pressure shows direct band gap along L point of the Brillouin zone.

scholarly journals Structural and Electronic Properties of Orthorhombic Phase Bi2Se3 Based On First-Principles Study

2019 ◽  
Vol 16 (2) ◽  
pp. 77 ◽  
Author(s):  
Muhammad Zamir Mohyedin ◽  
Afiq Radzwan ◽  
Mohammad Fariz Mohamad Taib ◽  
Rosnah Zakaria ◽  
Nor Kartini Jaafar ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Computer Code ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Percentage Difference ◽  
Structural And Electronic Properties

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.

scholarly journals 5f Delocalization of Bulk FCC Americium and the (111) Surface: A FP-LAPW Electronic Structure Study

2005 ◽  
Vol 893 ◽  
Author(s):  
Da Gao ◽  
Asok K Ray
Keyword(s):  
Electronic Properties ◽  
Local Density ◽  
Structure Study ◽  
Orbit Coupling ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Generalized Gradient ◽  
Quantum Size ◽  
Ferromagnetic Ground State

AbstractThe electronic properties of bulk fcc americium and the (111) surface have been investigated with the full-potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2K suite of programs The study is carried out for the anti-ferromagnetic ground state of Am at different levels of theory: (1) scalar-relativity vs. full-relativity; (2) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that spin orbit coupling plays an important role in determining the electronic properties of both bulk fcc americium and the (111) surface. In general, LDA is found to give a higher total energy compared to GGA results. The spin orbit coupling shows a similar effect on the surface calculations regardless of the model, GGA versus LDA. The 5f localized-delocalized transition of americium is employed to explain our results. In addition, the quantum size effects in the surface energies and the work functions of fcc (111) americium ultra thin films (UTF) are also examined.

Ab initio study of structural, mechanical, thermal and electronic properties of perovskites Sr(Li,Pd)H3

2016 ◽  
Vol 30 (04) ◽  
pp. 1650003 ◽  
Author(s):  
S. Benlamari ◽  
S. Amara Korba ◽  
S. Lakel ◽  
H. Meradji ◽  
S. Ghemid ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Electronic Properties ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Velocity Variation ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

The structural, elastic, thermal and electronic properties of perovskite hydrides SrLiH3 and SrPdH3 have been investigated using the all-electron full-potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). For the exchange-correlation potential, local-density approximation (LDA) and generalized gradient approximation (GGA) have been used to calculate theoretical lattice parameters, bulk modulus, and its pressure derivative. The present results are in good agreement with available theoretical and experimental data. The three independent elastic constants [Formula: see text], [Formula: see text] and [Formula: see text] are also reported. From electronic band structure and density of states (DOSs), it is found that SrLiH3 is an insulator characterized by an indirect gap of 3.48 eV, while SrPdH3 is metallic with a calculated DOSs at Fermi energy of 0.745 states/eV-unit cell. Poisson’s ratio [Formula: see text], Young’s modulus (E), shear modulus (G), anisotropy factor (A), average sound velocities [Formula: see text] and density [Formula: see text] of these compounds are also estimated for the first time. The Debye temperature is deduced from the average sound velocity. Variation of elastic constants and bulk modulus of these compounds as a function of pressure is also reported. Pressure and thermal effects on some macroscopic properties are predicted using the quasi-harmonic Debye model.

scholarly journals A study on structural and electronic properties of GaAs1-xNx and GaAs1-xBix alloys

2016 ◽  
Vol 4 (1) ◽  
pp. 6
Author(s):  
Metin Aslan ◽  
Battal Gazi Yalcin
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Local Density ◽  
Nitrogen Concentration ◽  
Potential Method ◽  
Generalized Gradient ◽  
Wide Range ◽  
Structural And Electronic Properties ◽  
Semiconductor Alloy ◽  
Ternary Semiconductor

<p>We have performed first principles method to investigate structural and electronic properties of GaAs<sub>1-x</sub>N<sub>x</sub> and GaAs<sub>1-x</sub>Bi<sub>x</sub> ternary semiconductor alloy using Density Functional Theory and pseudo potential method within the Generalized Gradient Approximations and Local Density Approximation. The Zinc-Blende phase is found stable for GaAsN and GaAsBi alloys. In this study we investigate the both bowing parameters changing with Bismuth concentration in GaAsBi and Nitrogen concentration in GaAsN alloys. By using the bowing parameter of GaAsBi and GaAsN alloys we obtained the bandgap energies for all x concentrations (0 &lt; x &lt; 1) and lattice constant of both alloys which are important for wide range device application. For studied materials, lattice parameters and band gap energies are compared with available theoretical and experimental works.</p>

High-pressure phases ofSiO2using local-density and generalized-gradient approximations

1997 ◽  
Vol 55 (17) ◽  
pp. 11003-11005 ◽  
Author(s):  
J. K. Dewhurst ◽  
J. E. Lowther ◽  
L. T. Madzwara
Keyword(s):  
High Pressure ◽  
Local Density ◽  
Generalized Gradient

FIRST-PRINCIPLES STUDY OF STRUCTURAL AND ELECTRONIC PROPERTIES OF SrLiSb UNDER HIGH PRESSURE

2012 ◽  
Vol 26 (29) ◽  
pp. 1250151
Author(s):  
Z. H. YU ◽  
C. Y. LI ◽  
H. Z. LIU
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Geometry Optimization ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Electronic Phase ◽  
Structural And Electronic Properties

Using the first-principles plane wave pseudopotential method, the structural and electronic properties of intermetallic compound SrLiSb have been studied within generalized gradient approximation in the frame of density functional theory. The calculations of lattice parameters are in well agreement with the available experimental data. The geometry optimization results indicated the compressibility of SrLiSb is anisotropic under high pressure. The energy band structure and density of states of SrLiSb were also calculated, indicating that SrLiSb has an electronic phase transition from direct-gap semiconductor to indirect-gap semiconductor at approximate 8 GPa.

FIRST-PRINCIPLES STUDY OF STRUCTURAL AND ELECTRONIC PROPERTIES OF ALKALI METAL CHALCOGENIDES: M2CH [M: LI, NA, K, RB; CH: O, S, SE, TE]

2011 ◽  
Vol 25 (29) ◽  
pp. 3911-3925 ◽  
Author(s):  
S. M. ALAY-E-ABBAS ◽  
N. SABIR ◽  
Y. SAEED ◽  
A. SHAUKAT
Keyword(s):  
Alkali Metal ◽  
Electronic Properties ◽  
Structural Properties ◽  
Density Functional ◽  
Local Density ◽  
Structural Parameters ◽  
Metal Chalcogenides ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Electronic Band

Ground-state structural properties of alkali metal selenides and tellurides (M2X) [M: Li, Na, K, Rb; X: Se, Te] have been studied in the framework of density functional theory for the first time using local density approximation, Perdew–Burke–Ernzerhof generalized gradient approximation (GGA) and Wu–Cohen (WC) GGA parameterization schemes. Also structural properties of alkali metal oxides and sulfides (M2X) [M: Li, Na, K, Rb; X: O, S] have been reinvestigated using WC GGA. Electronic band structures of alkali metal chalcogenide compounds have been calculated using the aforementioned schemes as well as the modified GGA proposed by Engel and Vosko. The calculated structural parameters for all 16 materials have been compared with earlier theoretical and experimental results, and certain trends are discussed. Furthermore, electronic density of states for these compounds has also been presented herein and behavior in electronic properties analyzed. Li, K and Rb chalcogenides have been found to have indirect bandgap, whereas Na chalcogenides appear to have direct bandgap.

scholarly journals First Principles Calculation of the Stability of Iron Bearing Carbonates at High Pressure Conditions

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 54
Author(s):  
Jun Tsuchiya ◽  
Risa Nishida ◽  
Taku Tsuchiya
Keyword(s):  
High Pressure ◽  
High Spin ◽  
First Principles ◽  
Lower Mantle ◽  
Local Density ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Carbonate Minerals ◽  
Pressure Stability ◽  
The Stability

Carbonate minerals such as ferromagnesite (Mg,Fe)CO 3 are suggested to be a possible major deep-carbon host in the lower mantle, because ferromagnesite is possibly stabilized by Fe spin crossover under pressure. However, the behavior of Fe-bearing carbonates under lower mantle pressure conditions has not been suitably examined thus far. Thus, in this study, we investigate the high-pressure stability of ferromagnesite and possible high-pressure structures with the chemical composition of (Mg 0.833 Fe 0.167 )CO 3 via first principles calculation using internally consistent local density approximation with Hubbard parameter (LDA+U) method, which can more accurately account for the electronic state of Fe than the LDA and generalized gradient approximation (GGA) approaches. The enthalpy values obtained via our calculations suggest that (Mg 0.833 Fe 0.167 )CO 3 undergoes phase transition from the R 3 ¯ c structure (high spin) to the P 1 ¯ (high spin) at 50 GPa, and to C2/m (high-spin) structure above 80 GPa, under static 0 K conditions. Therefore, no spin transitions in these carbonate minerals is expected under the lower mantle pressure conditions.

scholarly journals Comparative study of the structural and electronic properties of orthorhombic CH3NH3PbI3 hybrid perovskite for solar cell applications

2021 ◽  
Vol 40 (4) ◽  
pp. 616-622
Author(s):  
T.C. Chibueze
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Local Density ◽  
Total Density ◽  
Generalized Gradient ◽  
Lead Iodide ◽  
Functional Theory ◽  
Hybrid Perovskite ◽  
Structural And Electronic Properties ◽  
Direct Band

The structural and electronic properties of orthorhombic methyl ammonium lead iodide (CH3NH3PbI3 ) were investigated using the first principles density functional theory within the local density approximation (LDA) and the generalized gradient approximation (GGA).The lattice parameters obtained using the GGA were slightly greater than that obtained using the LDA. The total density of states and the electronic structure of the compound show that it is a direct band gap semiconductor. Our results are in agreement with the previous experimental and theoretical results and suggests that orthorhombic CH3NH3PbI3 compound is very promising in photovoltaic energy harvesting.

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