Lattice dynamics of Ferroelectric TlInS2 crystal

2012 ◽  
Vol 90 (5) ◽  
pp. 407-412 ◽  
Author(s):  
K.R. Allakhverdiev ◽  
F.M. Hashimzade ◽  
D.A. Huseinova ◽  
M.A. Nizametdinova ◽  
G.S. Orudzhev ◽  
...  
Keyword(s):  
Lattice Dynamics ◽  
Density Functional ◽  
Structural Parameters ◽  
Plane Waves ◽  
Low Frequency ◽  
Equilibrium Structure ◽  
Functional Theory ◽  
Lattice Constants ◽  
Pseudopotential Approach ◽  
Structure Calculations

In this paper we present the results of ab initio first-principle calculations of the lattice dynamics of ternary TlInS2 semiconductor with highly anisotropic crystal structure. Calculations have been performed using the open-source code ABINIT on the basis of density functional theory within the plane-wave pseudopotential approach. The basis of plane waves was truncated at electron kinetic energy of 40 Ha. Integration over the Brillouin zone was carried out using a 2 × 2 × 2 grid. The equilibrium structure was determined by minimizing the total energy with respect to the lattice constants and the internal structural parameters. The results are discussed in terms of previously existing experimental data. It is shown that along the layer, the low-frequency acoustic branch displays the bending wave behavior that is typical for crystals having a layered structure.

scholarly journals First-Principle Studies of the Vibrational Properties of Carbonates under Pressure

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3644
Author(s):  
Yurii N. Zhuravlev ◽  
Victor V. Atuchin
Keyword(s):  
Density Functional ◽  
Structural Parameters ◽  
Low Frequency ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Lattice Constants ◽  
Atomic Displacements ◽  
Carbonate Ion ◽  
The Density Functional Theory ◽  
Out Of Plane

Using the density functional theory with the hybrid functional B3LYP and the basis of localized orbitals of the CRYSTAL17 program code, the dependences of the wavenumbers of normal long-wave ν vibrations on the P(GPa) pressure ν(cm−1) = ν0 + (dv/dP)·P + (d2v/dP2)·P and structural parameters R(Å) (R: a, b, c, RM-O, RC-O): ν(cm−1) = ν0 + (dv/dR) − (R − R0) were calculated. Calculations were made for crystals with the structure of calcite (MgCO3, ZnCO3, CdCO3), dolomite (CaMg(CO3)2, CdMg(CO3)2, CaZn(CO3)2) and aragonite (SrCO3, BaCO3, PbCO3). A comparison with the experimental data showed that the derivatives can be used to determine the P pressures, a, b, c lattice constants and the RM-O metal-oxygen, and the RC-O carbon-oxygen interatomic distances from the known Δν shifts. It was found that, with the increasing pressure, the lattice constants and distances R decrease, and the wavenumbers increase with velocities the more, the higher the ν0 is. The exceptions were individual low-frequency lattice modes and out-of-plane vibrations of the v2-type carbonate ion, for which the dependences are either nonlinear or have negative dv/dP (positive dv/dR) derivatives. The reason for this lies in the properties of chemical bonding and the nature of atomic displacements during these vibrations, which cause a decrease in RM-O and an increase in RC-O.

scholarly journals The Influence of Oxygen Substitution on the Optoelectronic Properties of ZnTe

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Imad Khan ◽  
Sajid Khan ◽  
Javid Iqbal ◽  
H. A. Rahnamaye Aliabad ◽  
Zahid Ali ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Plane Waves ◽  
Full Potential ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Lattice Constants ◽  
Linear Behavior ◽  
Oxygen Substitution ◽  
Theoretical Results

We communicate theoretical results of the structural, electronic, and optical properties ofZnOxTe1-x(0≤x≤1) in the zincblende structure. The calculations are performed using full potential linearized augmented plane waves (FP-LAPW) method, based on density functional theory (DFT). The structural properties are calculated with simple GGA (PBEsol), while the electronic and optical properties are calculated using mBJ-GGA. The mBJ-GGA is used to properly treat the active d-orbital in their valence shell. The ZnOTe alloy is highly lattice mismatched and consequently the lattice constants and bulk moduli largely deviate from the linear behavior. The calculated bandgaps are in agreement with the experimentally measured values, where the nature of bandgaps is direct for the whole range ofxexcept atx=0.25. We also calculate the bandgap bowing parameter from our accurate bandgaps and resolve the existing controversy in this parameter.

First principle study of the electronic properties of the magnetocaloric compound Gd5Si4

2014 ◽  
Vol 28 (13) ◽  
pp. 1450103 ◽  
Author(s):  
Zobeideh Momeni Larimi ◽  
Ahmad Amirabadizadeh ◽  
Ahmad Yazdani ◽  
Hadi Arabi
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Structural Parameters ◽  
Magnetic Moments ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Functional Theory ◽  
Lattice Constants ◽  
Effective Role ◽  
Linearized Augmented Plane Wave

The electronic structure and magnetic properties of the Gd 5 Si 4 compound have been investigated by the first principles full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) using the WIEN2k code. The Coulomb corrected local-spin density approximation (LSDA + U) in the self-interaction correction (SIC) has been used for the exchange-correlation potential. Based on the calculated results, the ground state of Gd 5 Si 4 is found to be ferromagnetic (FM). The optimized structural parameters and magnetic properties including the lattice constants and magnetic moments are in good agreement with experimental data. The magnetic moments of the Gd atoms in Gd 5 Si 4 are smaller than that of the elemental gadolinium. The magnetic moment of Gd 5 Si 4 is found to be 37.8 μB/f.u. DOS results show that the magnetic properties of the compound depend on the hybridization between Si -3p and Gd -5d states which have an effective role in the RKKY interaction. The existence of the very flat bands at -7 eV for spin up and at +3 eV for spin down that is mainly Gd -4f characters shows that the LSDA + U method provides the better description of our systems. The obvious overlap of electron densities between the Gd1 and Si atoms indicates a covalent-like bonding between them.

STRUCTURAL PARAMETERS AND OPTOELECTRONIC PROPERTIES OF Mg-IV-V2 (IV=Si, Ge, Sn AND V=P, As) COMPOUNDS

2018 ◽  
Vol 25 (05) ◽  
pp. 1850108 ◽  
Author(s):  
M. IBRAHIM ◽  
HAYAT ULLAH ◽  
SAEED ULLAH JAN ◽  
MANZAR ALI ◽  
M. GULBAHAR ASHIQ
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Structural Parameters ◽  
Visible Region ◽  
Functional Theory ◽  
Lattice Constants ◽  
Direct Band Gap ◽  
Semiconductor Behavior ◽  
Direct Band

Semiconductors are the backbone of the optoelectronic industry. Direct band gap materials in the visible energy region are highly desirable for the efficient optoelectronic applications. In this work, we have probed the structural, electronic and optical properties of Mg-IV-V2 (IV[Formula: see text]Si, Ge, Sn and V[Formula: see text]P, As) compounds by FP-LAPW calculations, based on density functional theory. Their crystal structure is chalcopyrite with space group of I-42d. The lattice constants of MgSiP2, MgSiAs2 and MgGeAs2 are consistent with experimental results. These compounds show semiconductor behavior with direct band gap ranging from 1.3–2.15[Formula: see text]eV. Optical properties were also investigated. Optical properties include real and imaginary parts of dielectric constant, energy loss function, refraction and reflection. Direct band gap nature and good response in the visible region of these compounds predict their usefulness in optoelectronic devices.

Ab initio investigations of structural and electronic properties of AlSc3

2014 ◽  
Vol 03 (04) ◽  
pp. 1450019 ◽  
Author(s):  
K. L. Galav ◽  
K. B. Joshi
Keyword(s):  
Experimental Data ◽  
Electronic Properties ◽  
Density Functional ◽  
Structural Parameters ◽  
Electronic Band ◽  
Functional Theory ◽  
Lattice Constants ◽  
Structural And Electronic Properties ◽  
Murnaghan Equation ◽  
Electronic Band Structures

In this paper, structural and electronic properties of L12 and D019- AlSc 3 are presented. Calculations are performed applying crystalline orbital program within the framework of density functional theory. The exchange and correlation are treated following the Perdew–Becke–Ernzerhof ansatz. Other Al – Sc intermetallic compounds and polymorphs of Al 3 Sc , Al 2 Sc and AlSc are also investigated. The total energy calculations are coupled with the Murnaghan equation of state to determine lattice constants and bulk moduli. The data for D019- AlSc 3 are provided while deduced structural parameters for other materials are compared with the available results. Current results are reasonably in agreement with the experimental data and other reported calculations. Electronic band structures of a few Al – Sc compounds are studied with a view to examine effect of Al concentration on the formation of bands and bonds in the Al – Sc system.

Ab Initio Study of the Ge3N4 Semiconductor Materials in its Cubic γ Phase: A Computer Simulation

2013 ◽  
Vol 738 ◽  
pp. 22-25
Author(s):  
Chao Xu ◽  
Dong Chen
Keyword(s):  
Ab Initio ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Semiconductor Materials ◽  
Displacement Method ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Lattice Constants ◽  
Generalized Gradient Approximation ◽  
Good Agreement

The structural and elastic properties of the cubic spinel Ge3N4 semiconductor have been investigated using the ab initio scheme within the generalized gradient approximation in the framework of density functional theory. Quantities such as lattice constants and elastic constants of interest are calculated. A good agreement is found between our results and the other data. Through the lattice dynamics, in which the finite displacement method is used, we have obtained successfully the thermal properties such as the phonon curve, free energy, heat capacity and Debye temperature in the whole temperature range from 0 to 1000K. It is the authors ambition that these results will inspire further experimental study on the Ge-based semiconductors. * Corresponding author: CHEN Dong

scholarly journals Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5970
Author(s):  
Nabil Al-Zaqri ◽  
Mohammed Suleiman ◽  
Anas Al-Ali ◽  
Khaled Alkanad ◽  
Karthik Kumara ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Structural Parameters ◽  
Population Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Optical Energy Gap ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

scholarly journals Study of Anharmonicity in Zirconium Hydrides Using Inelastic Neutron Scattering and Ab-Initio Computer Modeling

Inorganics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 29
Author(s):  
Jiayong Zhang ◽  
Yongqiang Cheng ◽  
Alexander I. Kolesnikov ◽  
Jerry Bernholc ◽  
Wenchang Lu ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Excited States ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Vibrational States ◽  
Functional Theory ◽  
Hydrogen Deuterium ◽  
Zirconium Hydrides

The anharmonic phonon behavior in zirconium hydrides and deuterides, including ϵ-ZrH2, γ-ZrH, and γ-ZrD, has been investigated from aspects of inelastic neutron scattering (INS) and lattice dynamics calculations within the framework of density functional theory (DFT). The harmonic model failed to reproduce the spectral features observed in the experimental data, indicating the existence of anharmonicity in those materials and the necessity of further explanations. Here, we present a detailed study on the anharmonicity in zirconium hydrides/deuterides by exploring the 2D potential energy surface of hydrogen/deuterium atoms and solving the corresponding 2D single-particle Schrödinger equation to obtain the eigenfrequencies, which are then convoluted with the instrument resolution. The convoluted INS spectra qualitatively describe the anharmonic peaks in the experimental INS spectra and demonstrate that the anharmonicity originates from the deviations of hydrogen potentials from quadratic behavior in certain directions; the effects are apparent for the higher-order excited vibrational states, but small for the ground and first excited states.

scholarly journals Active binary switching of soft colloids: stability and structural properties

Soft Matter ◽  
2021 ◽  
Author(s):  
Michael Bley ◽  
Joachim Dzubiella ◽  
Arturo Moncho Jorda
Keyword(s):  
Density Functional Theory ◽  
Phase Behavior ◽  
Structural Properties ◽  
Brownian Dynamics ◽  
Density Functional ◽  
Equilibrium Structure ◽  
Functional Theory ◽  
Binary Switching ◽  
Soft Colloids ◽  
Non Equilibrium

We employ reactive dynamical density functional theory (R-DDFT) and reactive Brownian dynamics (R-BD) simulations to study the non-equilibrium structure and phase behavior of an active dispersion of soft Gaussian colloids...

scholarly journals First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1404
Author(s):  
Yunfei Yang ◽  
Changhao Wang ◽  
Junhao Sun ◽  
Shilei Li ◽  
Wei Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Vibrational Entropy ◽  
Functional Theory ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Ductile Behavior ◽  
Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

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