Electronic Structure vs Phase in Al3V

1988 ◽  
Vol 141 ◽  
Author(s):  
J.-H. Xu
Keyword(s):  
Electronic Structure ◽  
Bulk Modulus ◽  
Total Energy ◽  
Crystal Structures ◽  
Lattice Constant ◽  
Density Of States ◽  
Phase Stability ◽  
Local Density ◽  
Young Modulus ◽  
Good Agreement

AbstractThe electronic structure of Al3V vs its two different crystal structures (DO22 and Ll2) were investigated using local density total energy approach. The calculated results of the total energy showed that in Al3V the tetragonal DO22 phase is energetically favored as compared to the cubic Ll2 phase, the total energy in the former case is about 60 mRy/F.U. lower than that in the later case. The calculated lattice constant (a=3.72 Å, c=8.20 Å) is in fairly good agreement with experiment (a=3.778 Å, c=8.326 Å),and the bulk modulus (1.3 Mbar) is comparable with the experimental Young modulus (150 GPa) for Al3Ti. Furthermore, it is interesting to note that the density of states at EF in the tetragonal DO22 phase (0.14 states/eV-F.U.) is about one order magnitude smaller than that in the Ll2 phase (2.89 states/eV-F.U.). The electronic structure of Al3V seems to be fairly satisfactory in explaining its phase stability.

Understanding The Nb-Ti-A1 System: First Principles Calculations

1994 ◽  
Vol 364 ◽  
Author(s):  
Michael J. Mehl
Keyword(s):  
High Temperature ◽  
Bulk Modulus ◽  
Total Energy ◽  
Crystal Structures ◽  
Lattice Constant ◽  
Density Of States ◽  
First Principles ◽  
First Principles Calculations ◽  
Electronic Density ◽  
Cubic Phases

AbstractThe discovery of ductile cubic phases in the Nb-Ti-Al system has led to increased study of these high-temperature intermetallics. I have performed first-principles calculations for ordered crystal structures in this system, paying particular attention to the Nb7Ti7Al2 structure. Somewhat surprisingly, the electronic density of states, lattice constant, and bulk modulus are nearly independent of the ordering of these materials, even though the changes in the total energy are significant.

Ab Initio Investigation of Structural and Electronic Properties of ErPb3 in AB3 Structure

2016 ◽  
Vol 28 ◽  
pp. 39-42 ◽  
Author(s):  
Shubha Dubey ◽  
Gitanjali Pagare ◽  
Ekta Jain ◽  
Sankar P. Sanyal
Keyword(s):  
Bulk Modulus ◽  
Total Energy ◽  
Electronic Properties ◽  
Density Of States ◽  
Experimental Results ◽  
Energy Calculation ◽  
Present Calculation ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Calculated Density

The structural properties and electronic properties of the intermetallic compound ErPb3 which crystallize in AuCu3 type structure (AB3) are studied by means of first principles total energy calculation using full potential linearized plane wave method (FP-LAPW) within the generalized gradient approximation of Perdew, Burke and Ernzrhof (PBE) and local spin density approximation (LSDA) for the exchange correlation functional and including spin magnetic calculation. The total energy is computed as a function of volume and fitted to the Birch-Murnaghan equation of state. The ground state properties of this compound such as equilibrium lattice parameter (a0), bulk modulus (B), and its pressure derivative (B’) are calculated and compared with the available experimental results. We find good agreement with the other theoretical and experimental results. For the compounds, the values of lattice constants obtained by PBE-GGA overestimates and by LSDA underestimates the available experimental values for the same, which verifies the reliability of the present calculation. The value obtained for the bulk modulus is 50.63 GPa. The analysis of electronic properties is achieved by the calculation of the band structures and the density of states in both the spin up and spin down modes, which show a metallic character of ErPB3 due to zero band gap. The values of calculated density of states are found to be 0.36 eV/states and 11.46 eV/states in spin-up and spin-down mode respectively. The calculated magnetic moment (μm) of ErPb3 is 2.06.

ELECTRONIC STRUCTURE AND OPTICAL PROPERTIES OF CRYSTALLINE C60

1992 ◽  
Vol 06 (06) ◽  
pp. 309-321 ◽  
Author(s):  
W.Y. CHING ◽  
MING-ZHU HUANG ◽  
YONG-NIAN XU ◽  
FANQI GAN
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Optical Spectrum ◽  
Local Density ◽  
Low Dielectric Constant ◽  
Experimental Measurements ◽  
Absorption Bands ◽  
Low Dielectric ◽  
Good Agreement

The electronic structure and optical properties of crystalline C 60 and their pressure dependence have been studied by first-principles local density calculations. It is shown that fcc C 60 has a low dielectric constant and an optical spectrum rich in structures. The spectrum shows five disconnected absorption bands in the 1.4 to 7.0 eV region with sharp structures in each band that can be attributed to critical point transitions. This is a manifestation of the localized molecular structure coupled with long range crystalline order unique to the C 60 crystal. At a sufficient high pressure, the structures in the optical spectrum start to merge due to the merging of the bands. These results are in good agreement with some recent experimental measurements.

scholarly journals Theoretical design of a technetium-like alloy and its catalytic properties

2019 ◽  
Vol 10 (21) ◽  
pp. 5461-5469
Author(s):  
Wei Xie ◽  
Michihisa Koyama
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Catalytic Activity ◽  
Density Of States ◽  
Phase Stability ◽  
Density Functional ◽  
Catalytic Properties ◽  
Functional Theory ◽  
Theoretical Design ◽  
Structure Phase

Based on the concept of density of states (DOS) engineering, we theoretically designed a pseudo-Tc material (Mo–Ru alloy) and investigated its electronic structure, phase stability and catalytic activity by using density functional theory.

Molecular and electronic structure of ozone and thiozone from LCAO local density calculations

1985 ◽  
Vol 63 (7) ◽  
pp. 1982-1987 ◽  
Author(s):  
Mario Morin ◽  
Aniko E. Foti ◽  
Dennis R. Salahub
Keyword(s):  
Electronic Structure ◽  
Ground State ◽  
Local Minimum ◽  
Local Density ◽  
Molecular And Electronic Structure ◽  
Ground State Geometry ◽  
Good Agreement

LCAO local density calculations for ozone yield a ground state geometry in good agreement with experiment (R = 1.27 Å vs. 1.278 Å (exp.), θ = 117.5° vs. 116.8° (exp.)). A second local minimum is found about 45 kcal/mol higher for a cyclic geometry (R = 1.44 Å, θ = 60°). For S3 the calculations predict a bent ground state (R = 2.00 Å, θ = 116°) with the cyclic geometry (R = 2.125 Å, θ = 58°) about 15 kcal/mol higher.

Study on the Effect of Doping on Lattice Constant and Electronic Structure of Bulk AuCu by the Density Functional Theory

2019 ◽  
Vol 11 (02) ◽  
pp. 2030001 ◽  
Author(s):  
Dung Nguyen-Trong ◽  
Cuong Nguyen-Chinh ◽  
Van Duong-Quoc
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Electronic Properties ◽  
Lattice Constant ◽  
Density Of States ◽  
Impurity Concentration ◽  
Density Functional ◽  
Unit Cell ◽  
Functional Theory ◽  
The Density Functional Theory

This paper studies the effect of GGA-PBE, GGA-PBEsol, GGA-PW91, GGA-VWN-BP, LDA-PWC, LDA-VWN parameterized exchange–correlation functionals and Cu impurity concentration on the lattice and electronic properties of bulk AuCu by the Density Functional Theory (DFT). The lattice properties are determined by the lattice constant, the unit cell volume and the total energy on unit cell. The electronic properties are determined by the band gap, the Partial Density of States (PDOS) and the total Density of States (DOS) of materials. The obtained results showed the effect of the interaction potential and the Cu impurity concentration on the lattice structure and the electronic structure of bulk AuCu.

First Principles Investigation of Electronic Structure, Chemical Bonding, Elastic and Optical Properties of Novel Rhenium Nitrides

2012 ◽  
Vol 512-515 ◽  
pp. 883-889
Author(s):  
Qing Lin Xia ◽  
Liu Xian Pan ◽  
Yuan Dong Peng ◽  
Li Ya Li ◽  
Hong Zhong Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Density Of States ◽  
Chemical Bonding ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Hexagonal Phase ◽  
Partial Density

we investigate the electronic structure, chemical bonding, optical and elastic properties of the novel rhenium nitrides, hexagonal phase re3n and re2n by using density-functional theory (dft) within generalized gradient approximation (gga). the calculated equilibrium lattice constants of both re3n and re2n are in reasonable agreement with the experimental results. the band structure along the higher symmetry axes in the Brillouin zone, the density of states (dos) and the partial density of states (pdos) are presented. the calculated energy band structures and dos show that re3n and re2n are metal compounds. The dos and pdos show that the dos at the fermi level (ef) is located at the bottom of a valley and originate mainly from the 5d electrons of re. population analyses suggest that the chemical bonding in re3n and re2n has predominantly covalent character with mixed covalent and ionic characteristics. the dielectric function, reflectivity, absorption coefficient, refractive index, electron energy-loss function and optical conductivity are presented in an energy range for discussing the optical properties of re3n and re2n. basic mechanical properties, such as elastic constants cij, bulk modulus b and shear modulus g are calculated. The young’s modulus e, poisson's ratio ν and bh/gh are also predicted. results conclude that the hexagonal phase re3n and re2n are mechanical stable and behaves in a ductile manner. polycrystalline elastic anisotropy is also derived from polycrystalline bulk modulus b and shear modulus g.

Electronic Structure of Pd doped InP

1992 ◽  
Vol 272 ◽  
Author(s):  
P. K. Khowash
Keyword(s):  
Electronic Structure ◽  
Density Of States ◽  
Cluster Model ◽  
Local Density ◽  
Energy Spectra ◽  
Valence Band Edge ◽  
Metal Impurities ◽  
Structure Of Metal ◽  
Self Consistent ◽  
Small Magnetic Moment

ABSTRACTThe electronic structure of metal impurities in III-V semiconductors are interesting because of their ability to create deep centers. We use a spin unrestricted self-consistent local density theory in a cluster model to calculate the charge distributions, one electron energy spectra and the density of states for pure InP and Pd doped InP, substituted at the In site. The pure semiconductor gap is calculated to be 1.44 eV in excellent agreement with the experimental value of 1.41 eV. A small magnetic moment of 0.561μB appears on the Pd site. The impurity introduces a levels of t2 character at 0.01 and 0.04 eV above the valence band edge.

SIZE DEPENDENCE OF THERMOELASTIC PROPERTIES OF NANOMATERIALS

2010 ◽  
Vol 09 (05) ◽  
pp. 537-542 ◽  
Author(s):  
R. KUMAR ◽  
MUNISH KUMAR
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Bulk Modulus ◽  
Size Dependence ◽  
Young Modulus ◽  
Theoretical Method ◽  
Thermoelastic Properties ◽  
Theory And Experiment ◽  
Good Agreement

A simple theoretical method is developed to study the size dependence of bulk modulus, Young modulus, and coefficient of volume thermal expansion of nanomaterials. We have considered different nanomaterials, viz., Ni (spherical, nanofilm), α-Fe (spherical), and Cu (nanowire). The results obtained are compared with the available experimental data. A good agreement between theory and experiment supports the validity of the model developed in the present work.

scholarly journals Electronic structure of biaxially strained wurtzite crystals GaN, AlN, and InN

1996 ◽  
Vol 1 ◽  
Author(s):  
J. A. Majewski ◽  
M. Städele ◽  
P. Vogl
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Valence Band ◽  
First Principles ◽  
Degrees Of Freedom ◽  
Local Density ◽  
Structural Parameters ◽  
Spin Orbit ◽  
Biaxial Strain ◽  
Valence Band State

We present first-principles studies of the effect of biaxial (0001)-strain on the electronic structure of wurtzite GaN, AlN, and InN. We provide accurate predictions for the valence band splittings as a function of strain which greatly facilitates the interpretation of data from samples with unintentional growth-induced strain. The present calculations are based on the total-energy pseudopotential method within the local-density formalism and include the spin-orbit interaction nonperturbatively. For a given biaxial strain, all structural parameters are determined by minimization of the total energy with respect to the electronic and ionic degrees of freedom. Our calculations predict that the valence band state Γ9(Γ6) lies energetically above the Γ7(Γ1) states in GaN and InN, in contrast to the situation in AlN. In all three nitrides, we find that the ordering of these two levels becomes reversed for some value of biaxial strain. In GaN, this crossing takes place already at 0.32% tensile strain. For larger tensile strains, the top of the valence band becomes well separated from the lower states. The computed crystal-field and spin-orbit splittings in unstrained materials as well as the computed deformation potentials agree well with the available experimental data.

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