Structural, Electronic, and Magnetic Properties of Surfaces, Interfaces, and Superlattices

1985 ◽  
Vol 63 ◽  
Author(s):  
Arthur J. Freeman ◽  
C. L. Fu ◽  
T. Oguchi
Keyword(s):  
Total Energy ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Complex Materials ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Local Density Functional Theory ◽  
Flapw Method ◽  
Linearized Augmented Plane Wave

ABSTRACTAdvances in all-electron local density functional theory approaches to complex materials structure and properties made possible by the implementation of new computational/theoretical algorithms on supercomputers are exemplified in our full potential linearized augmented plane wave (FLAPW) method. In this total energy self-consistent approach, high numerical stability and precision (to 10 in the total energy) have been demonstrated in a study of the relaxation and reconstruction of transition metal surfaces. Here we demonstrate the predictive power of this method for describing the structural, magnetic and electronic properties of several systems (surfaces, overlayers, sandwiches, and superlattices).

Formation and stability of enhanced superhard nanostructured AlN/VN and AlN/TiN superlattice materials

2002 ◽  
Vol 750 ◽  
Author(s):  
C. Stampfl ◽  
A. J. Freeman
Keyword(s):  
Density Functional ◽  
Interface Energy ◽  
Accurate Estimate ◽  
Full Potential ◽  
Wurtzite Phase ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Rocksalt Phase ◽  
Flapw Method ◽  
Linearized Augmented Plane Wave

ABSTRACTUsing density functional theory and the full-potential linearized augmented plane wave (FLAPW) method, we investigate the formation and stability, and atomic structure, of rocksalt AlN/TiN and AlN/VN systems, including properties of the clean surfaces of the constituent materials. Calculations of the adlayer formation energy highlights the effect and interplay of the various energetic contributions on the growth of these strained systems, where the so-called “surface-interface” interaction energy is found to be important for the initial stages of AlN epitaxy. A significant strain energy builds up for increasing number of layers, where it is greater in the AlN/TiN system, which limits the thickness of rocksalt AlN regions that can grow before a structural transition to the lower energy wurtzite phase takes place. From our calculations, together with the known experimental critical thicknesses, we can obtain an accurate estimate of the wurtzite/substrate interface energy. That these values are high explains why the metastable rocksalt phase, which has significantly lower interface energies, is stabilized.

ALL-ELECTRON LOCAL-DENSITY DETERMINATION OF THE ELECTRONIC STRUCTURE AND SURFACE ENERGY OF ZR(0001)

1993 ◽  
Vol 07 (01n03) ◽  
pp. 520-523
Author(s):  
J. I. LEE ◽  
S. K. HWANG ◽  
S. C. HONG ◽  
A. J. FREEMAN
Keyword(s):  
Electronic Structure ◽  
Surface Energy ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Functional Theory ◽  
Plane Wave Method ◽  
Local Density Functional Theory ◽  
Linearized Augmented Plane Wave

The electronic structure and surface energy of Zr(0001) is determined theoretically using the all-electron full-potential linearized augmented plane wave method based on local-density functional theory. We found the value of surface energy to be 1.6 J/m 2 which is comparable to the value estimated from experiments on liquid zirconium at the melting point. It is, however, much smaller than the surface energies of W(001), V(001) and bcc Co(001). The calculated valence charge density, workfunction, and layer projected density of states for Zr(0001) are also presented.

scholarly journals Structural, electronic, optical properties and first-principles calculations of Sr1-xCaxWO4 ceramics

2019 ◽  
Vol 9 (3) ◽  
pp. 199-211
Author(s):  
Mohammed Ait Haddouch ◽  
Youssef Tamraoui ◽  
Fatima-Ezzahra Mirinioui ◽  
Youssef Aharbil ◽  
Hicham Labrim ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Local Density ◽  
Solid State Reaction Method ◽  
Full Potential ◽  
X Ray Diffraction ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Linearized Augmented Plane Wave

A series of strontium calcium tungstates Sr1-xCaxWO4 powders with (x = 0; 0.25; 0.5; 0.75 and 1.0) were prepared by solid-state reaction method and analyzed by X-ray diffraction (XRD). All these compositions possess a tetragonal scheelite structure with I41/a space group. Raman active vibrational modes in the range from 20 to 1000 cm-1 of the series Sr1-xCaxWO4 with tetragonal structure exhibit 13 modes in arrangement with the Group theory analysis of structural Raman-active modes. The optical properties were investigated using the diffuse reflectance UV–visible absorbance spectrum. Based on Density Functional Theory (DFT) and using full Potential-linearized Augmented Plane Wave (FP-LAPW) method with the Local Density Approximation and the Generalized Gradient Approximation (GGA), implemented in the Wien2k package, we have investigated electronic and optical properties of all the compositions. The results indicate a decrease in the values of the optical direct bandgap (from 4.29 to 3.87 eV) with the increase of Ca into SrWO4 lattice, which is in good agreement with our experimental results.

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.

Structural, Electronic and Elastic Properties of CeTl Intermetallic Compound

2016 ◽  
Vol 28 ◽  
pp. 1-4
Author(s):  
Deepika Shrivastava ◽  
Sankar P. Sanyal
Keyword(s):  
Bulk Modulus ◽  
Elastic Properties ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Cscl Type ◽  
Linearized Augmented Plane Wave

The structural, electronic and elastic properties of CeTl with CsCl-type B2 structure have been investigated using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA) for exchange and correlation potential. The ground state properties such as lattice constant, bulk modulus and pressure derivative of bulk modulus have been calculated which are in good agreement with available experimental data. The band structure and density of state depict that 4f electrons of Ce element have dominant character in electronic conduction and are responsible for metallic character of CeTl. The charge density plot reveals that the metallic as well as ionic bonding exist between Ce and Tl atoms. The calculated elastic constants indicate that CeTl is mechanically stable in cubic B2 phase and found to be ductile in nature.

scholarly journals Energy-loss Function for Lead

2017 ◽  
Vol 27 (1) ◽  
pp. 65
Author(s):  
Hieu T. Nguyen-Truong ◽  
Tan-Tien Pham ◽  
Nam H. Vu ◽  
Dang H. Ngo ◽  
Hung M. Le
Keyword(s):  
Energy Loss ◽  
Loss Function ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Functional Theory ◽  
Energy Loss Function ◽  
Zero Momentum ◽  
Electron Energy Loss ◽  
Linearized Augmented Plane Wave

We study the energy-loss function for lead in the framework of the time-dependent density functional theory, using the full-potential linearized augmented plane-wave plus local orbitals method. The ab initio calculations are performed in the adiabatic local density approximation. The comparison between the obtained energy-loss function for zero momentum transfer with those from reflection electron energy loss spectroscopy measurements and from first-principles calculations shows good agreement.

Structural and Anisotropic Elastic Properties of Hexagonal YMnO3 in Low Symmetry Determined by First-Principles Calculations

2019 ◽  
Vol 297 ◽  
pp. 120-130 ◽  
Author(s):  
Abdelhakim Chadli ◽  
Mohamed Halit ◽  
Brahim Lagoun ◽  
Ferhat Mohamedi ◽  
Said Maabed ◽  
...  
Keyword(s):  
Density Functional ◽  
Ferromagnetic State ◽  
Hexagonal Structure ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
The Density Functional Theory ◽  
Anisotropic Elastic ◽  
Linearized Augmented Plane Wave

The structural, elastic and anisotropic properties for rare earth manganites compound YMnO3 in ferromagnetic state with hexagonal structure, have been investigated using the ab initio calculations based on the density functional theory, this calculations were based on the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA). The agreement of the DFT (FP-LAPW) calculations including internal atomic relaxations, with the experimental data is very good. Other relevant quantities such as elastic constants, shear modulus, Young’s modulus, Poisson’s ratio, anisotropy factors, sound velocity, and Debye temperature have been calculated and discussed.

Pressure Effect on the Electronic Properties of Cerium Monochalcogenides CeX (X=S, Se, Te) Using Modified Becke-Johnson Exchange Potential and LDA+U

2014 ◽  
Vol 925 ◽  
pp. 390-395
Author(s):  
Noureddine Amrane ◽  
Maamar Benkraouda
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Exchange Potential ◽  
Full Potential ◽  
Electronic Band ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
The Density Functional Theory ◽  
Linearized Augmented Plane Wave

We present a systematic and comparative study of the electronic properties of CeX monochalcogenides, The density of state (DOS) and electronic band structure of CeX (X=S, Se, Te) have been calculated using the full-potential linearized augmented plane-wave (FP-LAPW) + local orbital (lo) method based on the density functional theory (DFT), which is implemented in WIEN2k code. The trends in the high pressure behavior of these systems are discussed. Four approximations for the exchange-correlation functional have been used, the GGA's of Perdew-Burke-Ernzherhof. (PBE08) , Engel-Vosko (EV93), a modified version of the exchange potential proposed by Becke and Johnson (MBJ), and LDA+U is used to calculate the band gaps at different pressures. All methods allow for a description of the Ce f electrons as either localized or delocalized, it is found that the underestimations of the bandgap by means of LDA-GGA and Engel-Vosko are considerably improved by using the modified Becke-Johnson (MBJ) potential for all compounds in the series, On the other hand, LDA+U, method gives good results for the lighter chalcogenides, but it fails to give good results for the heavier cerium monochalcogenides.

Electronic Structure of K2Bi8Se13

2001 ◽  
Vol 691 ◽  
Author(s):  
Daniel I Bilc ◽  
Paul Larson ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Ordered Structures ◽  
Augmented Plane Wave ◽  
Space Group ◽  
Β Phase ◽  
Indirect Band Gap ◽  
Linearized Augmented Plane Wave

ABSTRACTK2Bi8 Se13 belongs to a class of complex Bi-Te-Se systems which show great potential for thermoelectric performance. This compound forms in two distinct phases α-K2Bi8 Se13 (triclinic with space group P-1) and β-K2Bi8 Se13 (monoclinic with space group P 21/m). In the β-phase, there is substantial disorder at four sites in the unit cell, occupied by two K and two Bi atoms. To understand the electronic properties of these two different phases we have carried out band structure calculations 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. Spin-orbit interaction (SOI) was incorporated using a second variational procedure. The α. phase is found to be a semiconductor with an indirect band gap of 0.47eV. For the β-phase we have chosen two different ordered structures. The system is a semi-metal for one of the structures whereas for the other, it is a narrow gap semiconductor with a gap of 0.38eV in the absence of SOI, but the gap collapses and the system becomes a semimetal with low density of states at the Fermi energy when SOI is included.

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