Electronic Structure and Compton Profiles of Tungsten

2008 ◽  
Vol 63 (10-11) ◽  
pp. 703-711 ◽  
Author(s):  
Babu Lal Ahuja ◽  
Ashish Rathor ◽  
Vinit Sharma ◽  
Yamini Sharma ◽  
Ashvin Ramniklal Jani ◽  
...  
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Theoretical Data ◽  
Surface Topology ◽  
Full Potential ◽  
Energy Bands ◽  
Functional Theory ◽  
Hartree Fock ◽  
Spin Polarized ◽  
Linearized Augmented Plane Wave

The energy bands, density of states and Compton profiles of tungsten have been computed using band structure methods, namely the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) approach as well as the linear combination of atomic orbitals with Hartree-Fock scheme and density functional theory. The full potential linearized augmented plane wave scheme to calculate these properties and the Fermi surface topology (except the momentum densities) have also been used to analyze the theoretical data on the electron momentum densities. The directional Compton profiles have been measured using a 100 mCi 241Am Compton spectrometer. From the comparison, the measured anisotropies are found to be in good agreement with the SPR-KKR calculations. The band structure calculations are also compared with the available data.

Compton Profile Study of Aluminium Nitride

2007 ◽  
Vol 62 (12) ◽  
pp. 703-710 ◽  
Author(s):  
Vimal Vyas ◽  
Yogesh Chandra Sharma ◽  
Vinod Purvia ◽  
Narayan Lal Heda ◽  
Yamini Sharma ◽  
...  
Keyword(s):  
Density Functional ◽  
Population Analysis ◽  
Theoretical Data ◽  
Aluminium Nitride ◽  
Compton Profile ◽  
Energy Bands ◽  
Functional Theory ◽  
Hartree Fock ◽  
Ionic Nature ◽  
Γ Rays

In this paper we report the ab-initio theoretical Compton profiles of aluminium nitride (AlN) in the framework of the Hartree-Fock, density functional theory and hybridization of Hartree-Fock to density functional theories using the CRYSTAL03 code. To compare our first ever theoretical data, we have also measured the isotropic Compton profile of AlN, using 59.54 keV γ -rays. The Hartree- Fock scheme-based Compton profile agrees better with the experiment than the other theories. The energy bands, density of states and Mulliken’s population analysis, using the CRYSTAL03 code, are also reported. Our band structure calculations show a large band gap, while Mulliken’s population analysis shows the ionic nature of bonding in AlN.

Electronic Structure for Europium Chalcogenides with Modified Becke–Johnson Potential Plus an On-Site Coulomb U (mBJ+U)

SPIN ◽  
2018 ◽  
Vol 08 (04) ◽  
pp. 1850015
Author(s):  
S. Belhachi
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Full Potential ◽  
Semiconducting Materials ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Relativistic Spin ◽  
Spin Polarized ◽  
Experimental Values ◽  
Linearized Augmented Plane Wave

The full potential linearized-augmented-plane-wave (FP-LAPW) method is generalized to a case of an all-electron fully-relativistic spin-polarized self-consistent band calculation based on the relativistic spin-density functional theory and the modified Becke–Johnson potential (TB-mBJ) plus an on-site coulomb U employed for greater generation of the band gap. The results show that these materials are semiconducting materials. The indirect energy gap obtained in this calculation is 1.63[Formula: see text]eV, 1.79[Formula: see text]eV and 1.96[Formula: see text]eV for EuS, EuSe and EuTe, respectively. It is clear from the plots that LSDA[Formula: see text][Formula: see text][Formula: see text]U is a poor technique for the calculation of the band gaps of chalcogenides (EuX). The calculated results for EuX (S, Se and Te) by mBJ[Formula: see text][Formula: see text][Formula: see text]U are in good agreement with the experimental values as compared to the other calculated results.

Electronic structures, elastic, magnetic properties and half-metallicity in PtONa3 anti-perovskite

2019 ◽  
Vol 33 (29) ◽  
pp. 1950362 ◽  
Author(s):  
Oum Elkheir Youb ◽  
Zoubir Aziz ◽  
Feyza Zahira Meghoufel ◽  
Bouadjemi Boubdellah ◽  
Djoher Chenine ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Half Metallicity ◽  
Metallic Behavior ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spin Polarized ◽  
Linearized Augmented Plane Wave

The structural, elastic, electronic and magnetic properties of the cubic [Formula: see text] anti-perovskite are investigated by means of the full-potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). We have used three approximations: the generalized gradient (GGA), the GGA+[Formula: see text][Formula: see text], where [Formula: see text] is on-site Coulomb interaction correction, and the modified Becke–Johnson (mBJ-GGA). The elastic constants [Formula: see text] show that our compounds are ductile and anisotropic. The results obtained for the spin-polarized band structure and the density of states show a half-metallic behavior for the compounds using the GGA, GGA+[Formula: see text][Formula: see text] and mBJ-GGA approaches. These results make [Formula: see text] a promising candidate for spintronics applications.

scholarly journals Structural, Elastic and Thermal Properties of Lanthanide Monoantimonides

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Thermal Properties ◽  
Density Functional ◽  
Theoretical Data ◽  
Full Potential ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Cauchy Pressure ◽  
The Density Functional Theory ◽  
G Ratio ◽  
Linearized Augmented Plane Wave

Structural, elastic and thermal properties of lanthanide monoantimonides LnSb (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) compounds have been studied theoretically using full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) method within the density functional theory. The structural properties are investigated by using GGA-PBEsol scheme. We calculated bulk modulus, shear modulus, Young’s modulus, anisotropic ratio, Kleinman parameters, Poisson’s ratio, Lame’s co-efficient, sound velocities for shear and longitudinal waves, and Debye temperature. We also predict the Cauchy pressure and B/G ratio in order to explore the ductile and brittle behaviors of these compounds.Our results are in good agreement with available experimental and other theoretical data and also provide predictions where no experimental or theoretical results are available.

Calculation of Structural, Electronic and Optical Properties of Double Perovskite Ca2CrNbO6

SPIN ◽  
2021 ◽  
pp. 2150012
Author(s):  
W. Benosmane ◽  
S. Benatmane ◽  
R. Bentata ◽  
W. Benstaali
Keyword(s):  
Density Functional ◽  
Double Perovskite ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Generalized Gradient Approximation ◽  
Spin Polarized ◽  
Optical Dielectric ◽  
Linearized Augmented Plane Wave

The structural electronic and magnetic properties of the double perovskite Ca2CrNbO6 in the cubic structure are investigated using the empirical full-potential linearized augmented plane wave (FP-LAPW) method within the framework of the spin-polarized density functional theory (DFT). These properties are calculated using the Generalized Gradient Approximation (GGA), [Formula: see text] and modified Becke–Johnson mBJ-GGA. In addition, the real and imaginary parts of the optical dielectric function and the reflectivity, and the refractive spectra are computed and the main features shown by their spectra are ascertained on the base of the investigation of density of states.

First-principles calculations for optical investigations of PbX (X = S, Te) compounds under quantum dots diameter effect

2015 ◽  
Vol 93 (12) ◽  
pp. 1490-1494 ◽  
Author(s):  
Y. Al-Douri ◽  
H. Khachai ◽  
R. Khenata ◽  
A. Bouhemadou
Keyword(s):  
Quantum Dot ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Data ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Linearized Augmented Plane Wave

The full potential-linearized augmented plane wave (FP-LAPW) method is implemented in WIEN2K code to calculate the indirect energy gap (Γ–X) using density functional theory. The Engel–Vosko generalized gradient approximation (EVGGA) and modified Becke–Johnson (mBJ) formalisms are used to optimize the corresponding potential for energetic transition and optical properties calculations of PbS and PbTe compounds as a function of quantum dot diameter and are used to test the validity of our model of quantum dot potential. The refractive index and optical dielectric constant are investigated to explore best applications for solar cells. The calculated results are in agreement with other experimental and theoretical data.

Electronic structure of the thermoelectric materials PbTe and AgPb18SbTe20 from first-principles calculations

2010 ◽  
Vol 25 (6) ◽  
pp. 1030-1036 ◽  
Author(s):  
Pengxian Lu ◽  
Zigang Shen ◽  
Xing Hu
Keyword(s):  
Band Structure ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Partial Density ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Scanning Transmission ◽  
Linearized Augmented Plane Wave

To investigate the effects of substituting Ag and Sb for Pb on the thermoelectric properties of PbTe, the electronic structures of PbTe and AgPb18SbTe20 were calculated by using the linearized augmented plane wave based on the density-functional theory of the first principles. By comparing the differences in the band structure, the partial density of states (PDOS), the scanning transmission microscope, and the electron density difference for PbTe and AgPb18SbTe20, we explained the reason from the aspect of electronic structures why the thermoelectric properties of AgPb18SbTe20 could be improved significantly. Our results suggest that the excellent thermoelectric properties of AgPb18SbTe20 should be attributed in part to the narrowing of its band gap, band structure anisotropy, the much extrema and large DOS near Fermi energy, as well as the large effective mass of electrons. Moreover, the complex bonding behaviors for which the strong bonds and the weak bonds are coexisted, and the electrovalence and covalence of Pb–Te bond are mixed should also play an important role in the enhancement of the thermoelectric properties of the AgPb18SbTe20.

Electronic Structure Of (AgSb)xPbn-2xTen

2003 ◽  
Vol 793 ◽  
Author(s):  
Daniel I Bilc ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Two Component System ◽  
Functional Theory ◽  
Covalent Interaction ◽  
Salt Structure ◽  
Linearized Augmented Plane Wave

ABSTRACTComplex quaternary chalcogenides (AgSb)xPbn-2xTen (0<x<n/2) are thought to be narrow band-gap semiconductors which are very good candidates for room and high temperature thermoelectric applications. These systems form in the rock-salt structure similar to the well known two component system PbTe (x=0). In these systems Ag and Sb occupy Pb sites randomly although there is some evidence of short-range order. To gain insights into the electronic structure of these compounds, we have performed electronic structure calculations in AgSbTe2 (x=n/2). These calculations were carried out within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (LAPW) method. The generalized gradient approximation (GGA) was used to treat the exchange and correlation potential. Spinorbit interaction (SOI) was incorporated using a second variational procedure. Since it is difficult to treat disorder in ab initio calculations, we have used several ordered structures for AgSbTe2. All these structures show semimetallic behavior with a pseudogap near the Fermi energy. Te and Sb p orbitals, which are close in energy, hybridize rather strongly indicating a covalent interaction between Te and Sb atoms.

Density Functional Theory Approach for Muon Sites Estimation in Mn3Sn

2021 ◽  
Vol 1028 ◽  
pp. 199-203
Author(s):  
Fiqhri Heda Murdaka ◽  
Edi Suprayoga ◽  
Abdul Muizz Pradipto ◽  
Kohji Nakamura ◽  
Agustinus Agung Nugroho
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Theory Approach ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electrostatic Potential Calculation ◽  
A Site ◽  
Linearized Augmented Plane Wave

We report the estimation of muon sites inside Mn3Sn using density functional theory based on the full-potential linearized augmented plane wave (FLAPW) calculation. Our calculation shows that the Perdew–Burke–Ernzerhof (PBE) Generalized-Gradient Approximation (GGA) functional is closer to the experimental structure compared to the von Barth-Hedin Local Density Approximation (LDA)-optimized geometry. The PBE GGA is therefore subsequently used in FLAPW post-calculation for the electrostatic potential calculation to find the local minima position as a guiding strategy for estimating the muon site. Our result reveals at least two muon sites of which one is placed at the center between two Mn-Sn triangular layers (A site) and the other at the trigonal prismatic site of Sn atom (B site). The total energy of Mn3Sn system in the presence of muon at A site or B site are compared and we find that A site is a more favorable site for muon to stop.

Ab-initio thermodynamic and elastic properties of AlNi and AlNi3 intermetallic compounds

2018 ◽  
Vol 32 (11) ◽  
pp. 1850129 ◽  
Author(s):  
Shahram Yalameha ◽  
Aminollah Vaez
Keyword(s):  
Intermetallic Compounds ◽  
Elastic Properties ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Wide Range ◽  
Computational Data ◽  
Linearized Augmented Plane Wave

In this paper, thermodynamic and elastic properties of the AlNi and AlNi3 were investigated using density functional theory (DFT). The full-potential linearized augmented plane-wave (APW) in the framework of the generalized gradient approximation as used as implemented in the Wien2k package. The temperature dependence of thermal expansion coefficient, bulk modulus and heat capacity in a wide range of temperature (0–1600 K) were investigated. The calculated elastic properties of the compounds show that both intermetallic compounds of AlNi and AlNi3 have surprisingly negative Poisson’s ratio (NPR). The results were compared with other experimental and computational data.

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