scholarly journals Theoretical Investigation of the Electronic, Elastic, Vibration, Thermodynamic and Transport Properties of PtAsP Mixed Pyrite Phase

2021 ◽  
Vol 3 (1) ◽  
pp. 1-5
Author(s):  
Adewumi I. Popoola ◽  
B. Samuel Agboola
Keyword(s):  
Transport Properties ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Data ◽  
Incompressible Material ◽  
Debye Model ◽  
Elastic Vibration ◽  
Charge Carrier Concentration ◽  
Shear Moduli

Theoretical investigation on the elastic constants, phonon frequencies, thermodynamic and the transport properties of PtAsP mixed cubic pyrite phase was performed using the first-principles calculations based on the density functional theory. The calculated equilibrium crystal parameter is in excellent agreement with experimental data. The derived bulk and shear moduli are much higher than other theoretical data, suggesting that PtAsP may be a highly incompressible material. The detailed analyses of the electronic structures showed that PtAsP is an indirect energy gap compound and is elastically and dynamically stable. By using the harmonic Debye model, some thermodynamic properties including vibration free energy and constant volume heat capacity were calculated. The evaluation of the transport properties showed that PtAsP is a p-type material with capacity for improved performance when its charge carrier concentration is between 1016 cm3 and 1018 cm3.

DFT study of structural, elastic, electronic, magnetic, thermal and transport properties of new multifunctional NiVSn half-Heusler for spintronic and thermoelectric applications

2021 ◽  
pp. 2150202
Author(s):  
Y. Bouldiab ◽  
S. terkhi ◽  
Z. Aziz ◽  
F. Bendahma ◽  
M. A. Bennani ◽  
...  
Keyword(s):  
Transport Properties ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Extreme Temperature ◽  
Ferromagnetic State ◽  
Debye Model ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Half Metallic ◽  
High Seebeck Coefficient

In this work, the first-principles density functional calculations of the structural, elastic, electronic, magnetic, thermal and thermoelectric properties of NiVSn half-Heusler compound are carried out. The exchange and correlation potential are treated by using Generalized Gradient approximation of Perdew, Burke and Ernzerhof (GGA-PBE), GGA plus Tran–Blaha-modified Becke–Johnson (mBJ-GGA) approach and mBJ-GGA+U where U is the Hubbard on-site Coulomb interaction correction (mBJ-GGA+U). Structural calculations revealed that NiVSn is stable in type 1 structure ferromagnetic state. Elastic properties show that our compound is mechanically stable, ductile and anisotropic. The results of the band structures and density of states display a half metallic behavior of NiVSn with an indirect bandgap of 0.476, 0.508 and 0.845 eV by using GGA-PBE, mBJ-GGA, and mBJ-GGA+U, respectively. The total magnetic moment calculated is integer of 1 [Formula: see text]B confirming a half metallic behavior of NiVSn and follows the well-known Slater–Pauling rule ([Formula: see text]); therefore, the studied compound is suitable for application in spintronic fields. The thermodynamic properties such as bulk modulus, the heat capacity, the Debye temperature, and the thermal expansion coefficient are investigated using quasi-harmonic Debye model (QHDM). The thermal results show that NiVSn can be applied in extreme temperature and pressure conditions. The thermoelectric properties are studied employing the BoltzTrap code. The calculated transport properties are very interesting for the spin-down channel with high electrical conductivity, high Seebeck coefficient, and figure of merit value approaching unity. As a result, the half-Heusler alloy NiVSn is a promoter for conventional thermoelectric materials.

First-principles study on structural, elastic and thermal properties of γ-TiAl and α2-Ti3Al phases in TiAl-based alloy under high pressure

2017 ◽  
Vol 31 (11) ◽  
pp. 1750079 ◽  
Author(s):  
Chaoyan Zhang ◽  
Hua Hou ◽  
Yuhong Zhao ◽  
Xiaomin Yang ◽  
Yaqiong Guo
Keyword(s):  
High Pressure ◽  
Thermal Properties ◽  
Density Functional ◽  
Theoretical Data ◽  
Debye Model ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Two Phases ◽  
Calculated Equilibrium ◽  
Good Agreement

The structural, elastic and thermal properties of [Formula: see text]-TiAl and [Formula: see text]-Ti3Al phases in the TiAl-based alloy under pressure were reported using CASTEP program based on the density functional theory. The calculated equilibrium parameters and elastic constants are in good agreement with experimental and the available theoretical data. The results indicate that under the same pressure, the [Formula: see text] phase in the direction along [Formula: see text]-axis is easier to be compressed than the [Formula: see text] phase, while the compression along [Formula: see text]-axis of [Formula: see text] phase is larger than that of [Formula: see text] phase; when the pressure is below 20 GPa, both the two phases are elastically stable, but the [Formula: see text] phase have higher shear modulus and Young’s modulus, and the [Formula: see text] phase has better ductility and plasticity. Debye temperature, bulk modulus, thermal expansion coefficient and heat capacity of the [Formula: see text] phase and [Formula: see text] phase under high pressure and high temperature were also successfully calculated and compared using the quasi-harmonic Debye model in the present work.

The structures, phase transition and elastic and thermodynamic properties of ZnS from first-principles calculations

2021 ◽  
pp. 2150143
Author(s):  
Bo Li ◽  
Weiyi Ren
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Debye Model ◽  
Volume Curve ◽  
Temperature And Pressure

The phase transition of zinc sulfide (ZnS) from Zinc-blende (ZB) to a rocksalt (RS) structure and the elastic, thermodynamic properties of the two structures under high temperature and pressure are investigated by first-principles study based on the pseudo-potential plane-wave density functional theory (DFT) combined with the quasi-harmonic Debye model. The lattice constant [Formula: see text], bulk modulus [Formula: see text] and the pressure derivative of bulk modulus [Formula: see text]’ of the two structures are calculated. The results are in good agreement with experimental results and the other theoretical data. From the energy–volume curve, enthalpy equal principle and mechanical stability criterion, the transition pressures from the ZB to the RS structure are 16.83, 16.96 and 16.61 GPa, respectively. The three results and the experimental values 14.7–18.1, 16 GPa are very close to each other. Then the elastic properties are also calculated under the pressure ranging from 0 to 30 GPa. Finally, through the quasi-harmonic Debye model, the thermodynamic properties dependence of temperature and pressure in the ranges between 0–1600 K and 0–30 GPa are obtained successfully.

Theoretical investigation of energy gap bowing in CdSxSe1−x alloy quantum dots

2017 ◽  
Vol 19 (22) ◽  
pp. 14495-14502
Author(s):  
Laxman Tatikondewar ◽  
Anjali Kshirsagar
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Electronic Structure ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Energy Gap ◽  
Electronic Structure Calculations ◽  
Functional Theory ◽  
Alloy Quantum Dots ◽  
Structure Calculations

To investigate energy gap bowing in homogeneously alloyed CdSxSe1−x quantum dots (QDs) and to understand whether it is different from bulk, we perform density functional theory based electronic structure calculations for spherical QDs of different compositions x (0 ≤ x ≤ 1) and of varying sizes (2.2 to 4.6 nm).

scholarly journals Understanding Selectivities in Ligand-free Oxidative Cyclizations of 1,5- and 1,6-Dienes with RuO4 from Density Functional Theory

2010 ◽  
Vol 65 (3) ◽  
pp. 367-s400 ◽  
Author(s):  
Philipp J. di Dio ◽  
Stefan Zahn ◽  
Christian B.W. Stark ◽  
Barbara Kirchner
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Alkyl Chain ◽  
Energy Gap ◽  
Theoretical Data ◽  
Oxidative Cyclization ◽  
Transition Structure ◽  
Functional Theory ◽  
Oxidative Cyclizations ◽  
Ligand Free

Quantum-chemical calculations using density functional theory were carried out to investigate the mechanism of the oxidative cyclization of 1,5- and 1,6-dienes with ruthenium tetroxide. Current experimental results show different selectivities for the formation of tetrahydrofuran and tetrahydropyran derivatives. Our theoretical data correctly reproduce the experimental selectivities. Transition structures for the first [3+2]-cycloaddition of RuO4 with ethene and for the second [3+2]- cycloaddition with two ethene molecules, 1,5-hexadiene, and 1,6-heptadiene were calculated. For the formation of tetrahydrofuran and tetrahydropyran derivatives we observed two reaction pathways. The transition structure for the formation of cis-tetrahydrofuran derivatives was found to be more stable than the trans-tetrahydrofuran-forming transition structure by about 40 kJ mol−1. By comparison to the reaction with two ethene molecules it was shown that the linking alkyl chain causes the energy gap between stereoisomers by a directing influence. In the tetrahydropyran reaction the transtetrahydropyran- forming transition structure was less than 4 kJ mol−1 more stable than the transition structure leading to the cis-tetrahydropyran. The obtained geometries showed that for tetrahydropyrans the energy gap between stereoisomers is not caused by the linking alkyl chain.

scholarly journals A Computational Study of Optoelectronic and Charge Transport Properties of Purine Nucleobases Dinucleotides Compounds

2021 ◽  
Author(s):  
Kimberly Madison ◽  
Wojciech Kolodziejczyk ◽  
Karina Kapusta ◽  
Glake Hill
Keyword(s):  
Density Functional Theory ◽  
Charge Transport ◽  
Transport Properties ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Computational Study ◽  
Blue Shift ◽  
Functional Theory ◽  
Vertical Excitation

Abstract Optoelectronic and charge transport properties of eight novel compounds are presented in this work. Density functional theory B3LYP was utilized to optimize all structures while time-dependent density functional theory was utilized for vertical excitation characteristics. Gas and solvent phases (water, THF, and DCM) were evaluated to gain insight on solid-state and solution processed devices. While the solvent phases enhanced most of the charge transport properties, there was seen a blue-shift in their absorption wavelengths. However, C2, C4, C6, and C8 in THF absorption maxima were the highest and similar to those of the gas phase (605-652 nm). Extension of the polymer size decreased the HOMO-LUMO gap energy with C7 having the lowest energy gap in the gas phase. Although tuning the properties in optoelectronic devices is challenging, these findings will assist with the design of higher quality materials that could surpass the quality of inorganic devices.

scholarly journals Density functional prediction of the structural, elastic, electronic, and thermodynamic properties of the cubic and hexagonal (c, h)-Fe2Hf

10.30544/627 ◽  
2021 ◽  
Author(s):  
M Hemici ◽  
T Chihi ◽  
M A Ghebouli ◽  
FATMI Messaoud ◽  
B Ghebouli ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Density Functional ◽  
Pressure Range ◽  
Theoretical Data ◽  
Elastic Stability ◽  
Debye Model ◽  
Generalized Gradient ◽  
Wide Pressure Range ◽  
Mesh Density ◽  
Energy Convergence

Using density functional theory (DFT), the structural, elastic, electronic, and thermodynamic properties of Fe2Hf in the cubic and hexagonal solid phases with Fd-3m and P63/mmc are reported with generalized gradient approximations (GGA). To achieve energy convergence, we report the k-point mesh density and plane-wave energy cut-offs. The calculated equilibrium parameters are in good agreement with the available theoretical data. A complete elastic tensor and crystal anisotropies of the ultra-incompressible Fe2Hf are determined in the wide pressure range. Finally, by using the quasi-harmonic Debye Model, the isothermal and adiabatic bulk modulus and heat capacity of Fe2Hf are also successfully obtained in the present work. By the elastic stability criteria, it is predicted that Fd-3m and P63/mmc structures of Fe2Hf are stable in the pressure range studied, respectively.

The structure, elastic and thermodynamic properties of Ti2GaC from first-principles calculation

2019 ◽  
Vol 33 (06) ◽  
pp. 1950030 ◽  
Author(s):  
Xiao-Xia Pu ◽  
Xiao-Jiang Long ◽  
Lin Zhang ◽  
Jun Zhu
Keyword(s):  
Thermodynamic Properties ◽  
Elastic Constant ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Debye Model ◽  
First Principles Calculation

In this work, the structure, elastic and thermodynamic properties of Ti2GaC at high pressure (P) and high-temperature (T) are studied based on the density functional first-principles. The lattice parameters and elastic constants are well consistent with some theoretical data and experimental results. The elastic constant of Ti2GaC increase monotonously with the increase of pressure (P), which demonstrates the mechanical stability of Ti2GaC at the pressure (P) from 0 to 200 GPa. Mechanical properties including Poisson’s ratio ([Formula: see text]), Young’s modulus (E), shear modulus (G) and bulk modulus (B), which are obtained from elastic constants C[Formula: see text]. The ratio B/G value shows that Ti2GaC is a brittle material, but its enhancing ductility significantly with the elevate of pressure (P). The Grüneisen parameters ([Formula: see text]), thermal expansion coefficient ([Formula: see text]), heat capacity (C[Formula: see text]), elastic constant (C[Formula: see text]), bulk modulus (B), energy (E) and volume (V) with the change of temperature (T) or pressure (P) are calculated within the quasi-harmonic Debye model for pressure (P) and temperatures (T) range in 1600 K and 100 GPa. Besides, densities of states and energy band are also obtained and analyzed in comparison with available theoretical data.

First-principles calculations of structural, electronic and thermal properties of Zn1−x MgxS ternary alloys

Open Physics ◽  
2014 ◽  
Vol 12 (1) ◽  
Author(s):  
Samia Lamraoui ◽  
Rachid Bensalem ◽  
Khadidja Hacini ◽  
Hocine Meradji ◽  
Sebti Ghemid ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Density Functional ◽  
Small Deviation ◽  
Experimental Studies ◽  
Theoretical Data ◽  
Debye Model ◽  
Ternary Alloys ◽  
Full Potential ◽  
Generalized Gradient ◽  
Vegard’S Law

AbstractStructural, electronic and thermal properties of Zn1−x MgxS ternary alloys are studied by using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). The Wu-Cohen generalized gradient approximation (WC-GGA) is used in this approach for the exchangecorrelation potential. Moreover, the modified Becke-Johnson approximation (mBJ) is adopted for band structure calculations. The dependence of the lattice constant, bulk modulus and band gap on the composition x showed that the first exhibits a small deviation from the Vegard’s law, whereas, a marginal deviation of the second from linear concentration dependence (LCD). The bowing of the fundamental gap versus composition predicted by our calculations agrees well with the available theoretical data. The microscopic origins of the gap bowing are explained by using the approach of Zunger and co-workers. Thermal effects on some macroscopic properties of Zn1−x MgxS alloys are also investigated using the quasi-harmonic Debye model, in which the phononic effects are considered. As, this is the first quantitative theoretical prediction of the thermal properties of Zn1−x MgxS alloys, no other calculated results and furthermore no experimental studies are available for comparison.

scholarly journals Theoretical and experimental investigations into the structural, electronic, and molecular properties of 1,5-dihydropyrano[2,3-c]chromene derivatives

2019 ◽  
Vol 10 (3) ◽  
pp. 5586-5591
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Theoretical Calculations ◽  
Chemical Properties ◽  
Theoretical Data ◽  
Aromatic Aldehydes ◽  
Polarizable Continuum Model ◽  
Basis Set ◽  
Experimental Investigations ◽  
Three Component Reaction

In this study, a simple and efficient method for the synthesis of 1,5-dihydropyrano[2,3-c]chromene derivatives is reported by three component reaction of aromatic aldehydes, malononitrile, and 3-hydroxycoumarin in the presence of piperidine as base in ethanol, under reflux conditions. Also, the experimental results involving new and already synthesized compounds are compared with the theoretical calculations. The energy, molecular electrostatic potential (MEP), HOMO–LUMO energy gap, chemical properties and NMR analyses of 1,5-dihydropyrano[2,3-c]chromene derivatives in DMSO solution were estimated using density functional theory and 6-311++G (d,p) basis set. The solvent effect was explored using the polarizable continuum model (PCM) method. Increasing polarity and having no much difference in energies show the more effects of newly synthesized compounds (R2-DHPC) towards already synthesized compounds (R4-DHPC) in human body. Also, the results display that there is a good agreement between experimental and theoretical data.

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