The physical properties of ThCr2Si2-type superconductors MPd2P2 (M = Y, La): A theoretical investigation

2018 ◽  
Vol 32 (28) ◽  
pp. 1850312
Author(s):  
Md. Lokman Ali ◽  
Md. Tosaddek Hossen ◽  
Shahin Alam ◽  
Md. Sadek Hossain ◽  
Jakiul Islam ◽  
...  
Keyword(s):  
Experimental Data ◽  
Elastic Constants ◽  
Structural Data ◽  
Computer Code ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Anisotropic Factor ◽  
Optical Functions ◽  
Debye Temperatures ◽  
Ductile Behavior

The structural stability, elastic, mechanical, optical characteristics and Debye temperature of single crystalline superconductors MPd2P2 (M = Y, La) were investigated by using the ab initio technique. We have carried out the plane wave pseudopotential within the generalized gradient approximation (GGA) implemented in the CASTEP computer code. Our investigated results of structural data are in well consistent with the previous experimental data. The bulk modulus B, shear modulus G, Young’s modulus E, Poisson’s ratio v, hardness H, and anisotropic factor A of MPd2P2 (M = Y, La) compounds were evaluated from the calculated elastic constants. The analysis of ratio B/G shows that the MPd2P2 superconductors are in ductile behavior. The Debye temperatures are also investigated from the elastic constants. Finally, the optical functions including reflectivity, absorption coefficient, loss function, conductivity, refractive index, dielectric function are calculated and analyzed.

Optical and Transport Effects in LaGa1-xMnxO3: Experiment and Modeling

2004 ◽  
Vol 834 ◽  
Author(s):  
N. Noginova ◽  
F. Chen ◽  
G. Chelule ◽  
V. I. Gavrilenko
Keyword(s):  
Experimental Data ◽  
Density Functional ◽  
Energy Structure ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Optical Functions ◽  
Transport Effects ◽  
Electron Energy Structure ◽  
Theoretical Results

AbstractCharge transport and optical properties have been studied experimentally and theoretically in a series of LaGa1-xMnxO3 crystals in the dependence on the material composition. Electron energy structure and optical functions of LaGa1-xMnxO3 are calculated by ab initio pseudopotential method within density functional theory using generalized gradient approximation. Theoretical results are discussed in comparison with the experimental data for different alloy compositions.

First-Principles Investigation on Elastic Constants of TiN under High Pressure

2013 ◽  
Vol 802 ◽  
pp. 109-113
Author(s):  
Kittiya Prasert ◽  
Pitiporn Thanomngam ◽  
Kanoknan Sarasamak
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Local Density ◽  
Ambient Pressure ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Shear Distortion ◽  
Calculated Lattice Parameter

Elastic constants of NaCl-type TiN under pressure were investigated by first-principles calculations within both local density approximation (LDA) and Perdew-Burke-Ernzerhof generalized-gradient approximation (PBE-GGA). At ambient pressure, the calculated lattice parameter, bulk modulus, and elastic constants of NaCl-type TiN are in well agreement with other available values. Under pressure, all elastic constants,C11,C12, andC44, are found to increase with pressure.C11, which is related to the longitudinal distortion, increases rapidly with pressure whileC12andC44which are related to the transverse and shear distortion, respectively, are much less sensitive to pressure.

scholarly journals Thermodynamics of Uranium Tri-Iodide from Density-Functional Theory

2020 ◽  
Vol 10 (11) ◽  
pp. 3914
Author(s):  
Per Söderlind ◽  
Aurélien Perron ◽  
Emily E. Moore ◽  
Alexander Landa ◽  
Tae Wook Heo
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Heat Capacity ◽  
Density Functional ◽  
Thermodynamic Assessment ◽  
Harmonic Approximation ◽  
Metallic System ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation

Density-functional theory (DFT) is employed to investigate the thermodynamic and ground-state properties of bulk uranium tri-iodide, UI3. The theory is fully relativistic and electron correlations, beyond the DFT and generalized gradient approximation, are addressed with orbital polarization. The electronic structure indicates anti-ferromagnetism, in agreement with neutron diffraction, with band gaps and a non-metallic system. Furthermore, the formation energy, atomic volume, crystal structure, and heat capacity are calculated in reasonable agreement with experiments, whereas for the elastic constants experimental data are unavailable for comparison. The thermodynamical properties are modeled within a quasi-harmonic approximation and the heat capacity and Gibbs free energy as functions of temperature agree with available calculation of phase diagram (CALPHAD) thermodynamic assessment of the experimental data.

MODELLING OF NEUTRAL VACANCIES IN FORSTERITE MINERAL

2013 ◽  
Vol 27 (25) ◽  
pp. 1350141 ◽  
Author(s):  
ARVIDS STASHANS ◽  
YETZABEL FLORES
Keyword(s):  
Experimental Data ◽  
Chemical Bonding ◽  
Density Functional ◽  
Local Energy ◽  
Generalized Gradient ◽  
Covalent Character ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Interaction Law ◽  
Equilibrium Geometries

Density functional theory and generalized gradient approximation have been employed to study Mg , Si and O vacancies in the Mg 2 SiO 4 forsterite mineral. Microstructure of defect equilibrium geometries, electronic properties as well as chemical bonding in the region surrounding each one of the vacancies have been computed and discussed in detail. It is found that vacancies tend to increase covalent character of the chemical bonding for atoms situated in their vicinity independently of the type of vacancy. Nevertheless, obtained atomic distortion in the region surrounding vacancies generally obeys Coulomb electrostatic interaction law. Local energy states are found in the band-gap region due to the occurrence of vacancy-type defects. These findings are discussed in light of the available experimental data.

First-principles study of structural, elastic and thermodynamic properties of AuIn2

2015 ◽  
Vol 29 (34) ◽  
pp. 1550222 ◽  
Author(s):  
Hai Ying Wu ◽  
Ya Hong Chen ◽  
Chen Rong Deng ◽  
Peng Fei Yin ◽  
Hong Cao
Keyword(s):  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Pressure Effect ◽  
Structural Parameters ◽  
Text Structure ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Theoretical Results

The structural, elastic and thermodynamic properties of [Formula: see text] in the [Formula: see text] structure under pressure have been investigated using ab initio plane wave pseudopotential method within the generalized gradient approximation. The calculated structural parameters and equation of state are in excellent agreement with the available experimental and theoretical results. The elastic constants of [Formula: see text] at ambient condition are calculated, and the bulk modulus obtained from these calculated elastic constants agrees well with the experimental data. The pressure dependence of the elastic constants, bulk modulus, shear modulus and Young’s modulus has also been investigated. The Debye temperature presents a slight increase with pressure. [Formula: see text] exhibits ductibility and low hardness characteristics, the ductibility increases while the hardness decreases with the increasing of pressure. The pressure effect on the heat capacity and thermal expansion coefficient for [Formula: see text] is much larger.

Structural Stability and Chemical Bonding of TiN: Ab Initio Study

2014 ◽  
Vol 1047 ◽  
pp. 41-44
Author(s):  
Mamta Chauhan ◽  
Dinesh Chandra Gupta ◽  
Idris Hamid Bhat
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
High Pressure ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
B2 Phase ◽  
Pseudo Potential ◽  
Electronic Behavior

We have performed ab-initio calculations to investigate the structural and electronic behavior of TiN in the stable B1 and high pressure B2 phases using pseudo-potential plane wave approach within the framework of density functional theory. The calculated results show agreement with the experimental data. The present electronic behavior, determined by total energy calculations with generalized gradient approximation for exchange and correlation interactions, is observed to be similar in both B1 and B2 phases showing metallic, covalent as well as ionic bonding of TiN. The investigations in B2 phase need validation experimentally as well as theoretically.

scholarly journals Theoretical calculation for the phonon spectrum and thermodynamic functions of vanadium and its hydride

2021 ◽  
Vol 252 ◽  
pp. 03039
Author(s):  
Qiang Wei-rong ◽  
Wang Xiao-mei ◽  
Liu Wei-qi
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Free Energies ◽  
Generalized Gradient ◽  
Virtual Crystal Approximation ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Density Functional Perturbation Theory ◽  
Densities Of States

Based on density functional theory(DFT), using virtual crystal approximation and generalized gradient approximation(GGA)with pseudopotential method, the lattices and energies for five crystallines of vanadium hydrides are optimized and calculated. The phonon densities of states are calculated based on density functional perturbation theory(DFPT). The standard Heat capacities, Entropies, Helmholtz free energies and Gibbs functions of vanadium and its hydride are deduced at 298.15K. The calculated results are discussed and compared with experimental data.

Study of first principles on anisotropy and elastic constants of YAl3 compound

2020 ◽  
Vol 98 (4) ◽  
pp. 357-363
Author(s):  
Tahsin Özer
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Data ◽  
Anisotropic Behavior ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Quantum Espresso

Using the density functional theory (DFT) calculations, the structural optimization of the YAl3 compound was performed on the generalized gradient approximation (GGA) with quantum ESPRESSO (QE) software. Elastic constants were calculated after the optimization process. Polycrystalline quantities, such as bulk and shear modulus, Young’s modulus, and Poisson’s ratio, were determined using calculated elastic constants. The anisotropy of the compound was studied in detail. As a result of the calculations made, it was observed that the YAl3 compound exhibited mechanically stable structure and anisotropic behavior. In the ht2-YAl3 phase, the effect of pressure on physical properties was investigated in detail. The obtained results were compared with the existing experimental and other theoretical data.

First-principles investigation of the elastic and thermodynamic properties of ReC2 (Re = Ho, Nd, Pr)

2015 ◽  
Vol 29 (01) ◽  
pp. 1450256 ◽  
Author(s):  
Wen Huang ◽  
Haichuan Chen
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Lattice Constants ◽  
Generalized Gradient Approximation ◽  
Temperature Melting

The elastic and thermodynamic properties of Re C 2 (Re = Ho , Nd , Pr ) have been investigated by using the first-principles density functional theory within the generalized gradient approximation. The computed lattice constants of Re C 2 are in agreement with the experimental data. The calculated elastic constants reveal that all compounds are mechanically stable. The shear modulus, Young's modulus, Poisson's ratio σ, the ratio B/G, shear anisotropy and elastic anisotropy are also calculated. Finally, the Vicker hardness, Debye temperature, melting point and thermal conductivity have been predicted.

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