scholarly journals A First-Principles Study of Structure, Elastic and Electronic Properties of GeTiO3 as Environmentally Innocuous Ferroelectric Perovskites

2021 ◽  
Vol 66 (6) ◽  
pp. 539
Author(s):  
G.K. Shiferaw ◽  
M.W. Menberu
Keyword(s):  
Elastic Constant ◽  
Density Of States ◽  
Spontaneous Polarization ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Parameters ◽  
Theoretical Data ◽  
Lattice Parameter ◽  
Generalized Gradient ◽  
Electronic Band

The structural parameters, elastic properties, spontaneous polarization, electronic band structure, and density of states (DOS) of GeTiO3 in tetragonal phase have been studied computationally using pseudopotential plane-wave (PP-PW) method based on the density functional theory (DFT). The generalized gradient approximation (GGA) was used to estimate the exchange-correlation energies. The equilibrium lattice parameter, unit cell volume, bulk modulus and its derivative are obtained and compared with the available theoretical data. The elastic characteristics such as elastic constants, Poisson’s ratio, elastic modulus, and anisotropy factor are obtained in the pressure range 0–50 GPa. Our computed results of elastic constant satisfy Born’s stability criterion. In view of Pugh’s prediction standard, the material is taken as ductile. Once the elastic constant is calculated, the Debye temperature of GeTiO3 compound is also evaluated from the average sound velocity. The density of states, band structures, and charge-density distribution are discussed and compared with previous computational results. The calculation within Berry’s phase approach indicate a high spontaneous polarization of tetragonal GeTiO3 (1.125 C/m2). Thus, the substance is identifi ed as a promising environmentally friendly ferroelectric material.

scholarly journals First principle study of structural, elastic, electronic and optical properties of Pb0.5Sn0.5TiO3 and Pb0.5Sn0.5Ti0.5(Zr0.5)O3

2021 ◽  
Vol 24 (1) ◽  
pp. 13702
Author(s):  
S.G. Kuma ◽  
M.M. Woldemariam
Keyword(s):  
Optical Properties ◽  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Theoretical Data ◽  
Poisson's Ratio ◽  
Modern Theory ◽  
Generalized Gradient ◽  
Electronic Band

The structural, electronic, elastic and optical properties of tetragonal (P4mm) phase of Pb0.5Sn0.5TiO3 (PSTO) and Pb0.5Sn0.5Ti0.5(Zr0.5)O3 (PSTZO) are examined by first-principles calculations based on the density functional theory (DFT) using the pseudo-potential plane wave (PP-PW) scheme in the frame of generalized gradient approximation (GGA). We have calculated the ground state properties such as equlibrium lattice constants, volume, bulk modulus and its pressure derivative. From elastic constants, mechanical parameters such as anisotropy factor, elastic modulus and Poisson's ratio are obtained from the Voigt-Reuss-Hill average approximation. Rather than their averages, the directional dependence of elastic modulus, and Poisson's ratio are modelled and visualized in the light of the elastic properties of both systems. In addition, some novel results, such as Debye temperatures, and sound velocities are obtained. Moreover, we have presented the results of the electronic band structure, densities of states and charge densities. These results were in favourable agreement with the existing theoretical data. The optical dielectric function and energy loss spectrum of both systems are also computed. Born effective charge (BEC) of each atoms for both systems is computed from functional perturbation theory (DFPT). Finally, the spontaneous polarization is also determined from modern theory of polarization to be 0.8662 C/m2 (PSTO) and 1.0824 C/m2 (PSTZO).

First Principles Study on Structural and Electronic Properties of PZT and PSnZT Using Density Functional Theory

2016 ◽  
Vol 846 ◽  
pp. 734-739 ◽  
Author(s):  
N.H. Hussin ◽  
Mohamad Fariz Mohamad Taib ◽  
F.W. Badrudin ◽  
N.A. Johari ◽  
Nunshaimah Salleh ◽  
...  
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Geometry Optimization ◽  
Lone Pair ◽  
Lattice Parameter ◽  
Density Of State ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Indirect Band Gap

The geometry optimization of the tetragonal supercell 1x1x2 (P4mm, 99 space group) of PZT and PSnZT were calculated using different exchange correlation functional such as Local Density Approximate (LDA-CAPZ) and Generalized Gradient Approximation (GGA-PBE & GGA-PBEsol).The calculation using functional GGA-PBEsol exhibits the most accurate values of lattice parameter and volume of structure relative to the experiment results with typical error of approximately 1% underestimate (only for PZT-as reference materials). The electronic band structure and density of state (DOS) were also studied in order to understand the electron density and hybrization between cation and anion in the compound. The density of state studies indicated existing of hybridizations among anion O 2p, cation Pb 6s/Sn 5s (special lone pair) and the Ti 3d/Zr 4d states of PZT and PSnZT compound. An indirect band gap was respectively obtained for both cubic PZT and PSnZT at the F-G and Q-G point with 3.154 eV and 2.571 eV.

scholarly journals Structural, Electronic, Lattice Dynamic, and Elastic Properties of SnTiO3 and PbTiO3 Using Density Functional Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Shiferaw Kuma ◽  
Menberu Mengesha Woldemariam
Keyword(s):  
Bulk Modulus ◽  
Elastic Properties ◽  
Density Of States ◽  
Elastic Constants ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Electronic Band Structure ◽  
Theoretical Data ◽  
Modern Theory ◽  
Electronic Band

The structural, electronic, and elastic properties of tetragonal phase of SnTiO3 and PbTiO3 are investigated using first principle calculations. The unknown exchange-correlation functional is approximated with generalized gradient approximation (GGA) as implemented in pseudopotential plane wave approach. The convergence test of total energy with respect to energy cutoff and k-point sampling is preformed to ensure the accuracy of the calculations. The structural properties such as equilibrium lattice constant, equilibrium unit cell volume, bulk modulus, and its derivative are in reasonable agreement with the previous experimental and theoretical works. From elastic constants, mechanical parameters such as anisotropy factor A, shear modulus G, bulk modulus B, Young’s modulus E, and Poison’s ratio n are determined by using Voigt–Reuss–Hill average approximation. In addition, Debye temperature and longitudinal and transversal sound velocities are predicted from elastic constants. The electronic band structure and density of states of both compounds are obtained and compared with the available experimental as well as theoretical data. Born effective charge (BEC), phonon dispersion curve, and density of states are computed from functional perturbation theory (DFPT). Lastly, the spontaneous polarization is determined from the modern theory of polarization, and they are in agreement with the previous findings.

DFT-BASEDAB INITIOSTUDY OF THE ELECTRONIC AND OPTICAL PROPERTIES OF CESIUM BASED FLUORO-PEROVSKITECsMF3(M = CaANDSr)

2012 ◽  
Vol 26 (32) ◽  
pp. 1250199 ◽  
Author(s):  
M. HARMEL ◽  
H. KHACHAI ◽  
M. AMERI ◽  
R. KHENATA ◽  
N. BAKI ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Theoretical Data ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Structure Density

Density functional theory (DFT) is performed to study the structural, electronic and optical properties of cubic fluoroperovskite AMF3( A = Cs ; M = Ca and Sr ) compounds. The calculations are based on the total-energy calculations within the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential is treated by local density approximation (LDA) and generalized gradient approximation (GGA). The structural properties, including lattice constants, bulk modulus and their pressure derivatives are in very good agreement with the available experimental and theoretical data. The calculations of the electronic band structure, density of states and charge density reveal that compounds are both ionic insulators. The optical properties (namely: the real and the imaginary parts of the dielectric function ε(ω), the refractive index n(ω) and the extinction coefficient k(ω)) were calculated for radiation up to 40.0 eV.

ELECTRONIC STRUCTURE, DIELECTRIC AND DYNAMICAL PROPERTIES OF ZINC-BLENDE AlN FROM FIRST PRINCIPLES CALCULATION

2007 ◽  
Vol 21 (26) ◽  
pp. 1775-1784
Author(s):  
HUAN-YOU WANG ◽  
HUI XU ◽  
JIAN-RONG XIAO ◽  
MINGJUN LI
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Plane Wave Method ◽  
Zinc Blende

We have performed density-functional perturbation calculation for zinc-blende AlN using the pseudopotential plane-wave method. The results obtained using both the local-density approximate (LDA) and the generalized-gradient approximate (GGA) for exchange-correlation functional are compared. The ground state properties and response function properties for zinc-blende AlN , including the electronic band structure, charge density, Born effective charge, dielectric constant and vibrational properties are reported. Our results are basically in agreement with experimental data and theoretical values available, but the bandgap is underestimated and the first optical mode in the phonon band structure is overestimated. This can be attributed to the underestimation of the lattice parameter and selection of the pseudopotential.

scholarly journals Optimizing Configurations for Determining the Electromagnetic Properties of CsFeF3, NaFeF3, and RbFeF3 Fluorides: GGA vs GGA+U and TB-mBj Approaches

2020 ◽  
Vol 62 (1) ◽  
pp. 71-94
Author(s):  
Filalli Sihem ◽  
Hamdad Noura
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Parameters ◽  
Magnetic Moments ◽  
Plane Waves ◽  
Electromagnetic Properties ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Covalent Interaction

AbstractThe structural, electronic and magnetic properties of (Cubic Pm-3m, Hexagonal-4H, orthorhombic Pnma, and orthorhombic Pbnm) phases of AFeF3 Fluorides (A = Cs, Na, and Rb) are reported theoretically using full potential linearized augmented plane waves method within the density functional theory (DFT). Using different exchange–correlation approximations including the generalized gradient approximation (PBE-GGA, WC-GGA, and PBEsol-GGA), also (GGA) with Hubbard potential (GGA + U) and The modified Becke Johnson potential (mBJ), we carried to determine various physical properties. The Calculations revealing that the estimated structural parameters are reliable with the experimentally reported data. Magnetically all these intermetallics are Ferromagnetic (FM). The ground-state energy of different magnetic phases studied showed that the magnetic moments are evaluated per atom, and overestimated by (GGA+U). Transfer charge reveals a strong covalent interaction between Fe-Fe atoms. Their electronic band structure and density of states indicate insulator behavior.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

scholarly journals Electronic structure, Mechanical and Thermodynamic properties of CoYSb (Y= Cr, Mo, W) half-Heusler compounds as potential spintronic materials

2021 ◽  
Author(s):  
O. T. Uto ◽  
J. O. Akinlami ◽  
S. Kenmoe ◽  
G. A. Adebayo
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Covalent Bond ◽  
Stable Phase ◽  
Type I ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Electronic Band ◽  
Half Metallic

Abstract The CoYSb (Y = Cr, Mo and W) compounds which are XYZ type half-Heusler alloys and also exist in the face centred cubic MgAgAs-type struc-ture conform to F ̄43m space group. In the present work, these compoundsare investigated in different atomic arrangements called, Type-I, Type-II andType-III phases, using Generalized Gradient Approximation (GGA) in the Density Functional Theory (DFT) implemented in QE (Quantum EspressoAb-Initio Simulation Package). The ferromagnetic state of these alloys is studied after investigating their stable structural phase. The calculated electronic band structure and the total electronic density of states indicated nearly half-metallic behaviour in CoMoSb with a possibility of being used in spintronic application, metallic in CoWSb and half-metallic in CoCrSb, with the minority spin band gap of 0.81 eV. Furthermore, the calculated mechanical properties predicted an anisotropic behaviour of these alloys in the stable phase. Finally, due to its high Debye temperature value, CoCrSb possesses a stronger covalent bond than CoMoSb and CoWSb, respectively.

Structural, electronic and elastic properties of the B2-ScM (M =Au, Hg and Tl) intermetallic compounds: Ab initio calculations

2015 ◽  
Vol 04 (04) ◽  
pp. 1550020
Author(s):  
Ahmad A. Mousa ◽  
Jamil M. Khalifeh
Keyword(s):  
Mechanical Properties ◽  
Bulk Modulus ◽  
Intermetallic Compounds ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

Structural, electronic, elastic and mechanical properties of ScM (M[Formula: see text][Formula: see text][Formula: see text]Au, Hg and Tl) intermetallic compounds are studied using the full potential-linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT), within the generalized gradient approximation (GGA) and the local density approximation (LDA) to the exchange-correlation approximation energy as implemented in the Wien2k code. The ground state properties including lattice parameters, bulk modulus and elastic constants were all computed and compared with the available previous theoretical and experimental results. The lattice constant was found to increase in contrast to the bulk modulus which was found to decrease with every substitution of the cation (M) starting from Au till Tl in ScM. Both the electronic band structure and density-of-states (DOS) calculations show that these compounds possess metallic properties. The calculated elastic constants ([Formula: see text], [Formula: see text] and [Formula: see text] confirmed the elastic stability of the ScM compounds in the B2-phase. The mechanical properties and ductile behaviors of these compounds are also predicted based on the calculated elastic constants.

Electronic band structure of silver low-index surfaces: a tight-binding study

2020 ◽  
Vol 98 (5) ◽  
pp. 488-496
Author(s):  
H.J. Herrera-Suárez ◽  
A. Rubio-Ponce ◽  
D. Olguín
Keyword(s):  
Band Structure ◽  
Density Of States ◽  
Electronic Band Structure ◽  
Local Density ◽  
Tight Binding ◽  
Theoretical Data ◽  
Binding Study ◽  
Local Density Of States ◽  
Electronic Band ◽  
Tight Binding Method

We studied the electronic band structure and corresponding local density of states of low-index fcc Ag surfaces (100), (110), and (111) by using the empirical tight-binding method in the framework of the Surface Green’s Function Matching formalism. The energy values for different surface and resonance states are reported and a comparison with the available experimental and theoretical data is also done.

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