Computational investigations of mechanic, electronic and lattice dynamic properties of yttrium based compounds

2018 ◽  
Vol 32 (20) ◽  
pp. 1850214 ◽  
Author(s):  
Gökçen Dikici Yıldız ◽  
Yasin Göktürk Yıldız ◽  
Selgin AL ◽  
Ahmet İyigör ◽  
Nihat Arıkan

Electronic, mechanic and lattice dynamic properties of yttrium-based compounds, X3Y, where X = Pd, Pt and Rh were investigated using the density functional theory. The electronic band calculations demonstrated that X3Y compounds are metallic at the cubic crystal structures. The calculated elastic constants using the energy-strain method indicate that the three materials are mechanically stable. The calculated bulk modulus and Young’s modulus values suggest that the Pt3Y is stiffer than that of the other two. The type of bonding and ductility in the X3Y compounds were also evaluated based on their B/G ratios, Cauchy pressures (C[Formula: see text]–C[Formula: see text]) and band structure calculations. These compounds were found to be ductile in nature. The density functional perturbation theory was used to derive full phonon frequencies and total and projected phonon density of states. The computed full phonon spectra for X3Y compounds show that these compounds in the L12 phase are dynamically stable. Debye temperature and specific heat of these compounds were also calculated and evaluated using quasi harmonic approximation.

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sinem Erden Gulebaglan ◽  
Emel Kilit Dogan

Abstract To estimate the structural, electronic, elastic and dynamic properties of ZrInAu and ZrSnPt compounds, the density functional theory within the general gradient approximation was used. The computed lattice parameters, bulk modulus and the derivation of bulk modulus with respect to pressure were displayed and compared with the theoretical result. The indirect band gap for ZrInAu was found to be 0.48 eV, and for ZrSnPt the indirect band gap was found as 1.01 eV. Elastic stiffness constants, bulk, shear and Young’s module, Poisson’s coefficients and Zener anisotropy factor are calculated. Elastic properties showed that the ZrSnPt compound is more durable than the ZrInAu compound. Phonon distribution curves and density of states were investigated using a density functional perturbation theory. Both ZrInAu and ZrSnPt compounds were demonstrated to be dynamically stable. The results of this study were obtained for the first time in the literature. These results will make an important contribution to the literature.


2018 ◽  
Vol 32 (14) ◽  
pp. 1850169
Author(s):  
Leini Wang ◽  
Zhang Jian ◽  
Wei Ning

The phonon, elastic and thermodynamic properties of L12phase Rh3Ta have been investigated by the density functional theory (DFT) approach combined with the quasi-harmonic approximation model. The results of the phonon band structure show that L12phase Rh3Ta possesses dynamical stability in the pressure range from 0–80 GPa due to the absence of imaginary frequencies. The pressure dependences with the elastic constants C[Formula: see text], shear modulus G, bulk modulus B, Young’s modulus Y, Poisson’s ratio and B/G ratio have been analyzed. The results of the elastic properties studies show that L12phase Rh3Ta compound is mechanically stable and possesses a higher hardness, improved ductility and plasticity under higher pressures. The pressure and temperature relationship of the thermodynamic properties, such as the Debye temperature [Formula: see text], heat capacity C[Formula: see text], thermal expansion coefficient [Formula: see text] and the Grüneisen parameter [Formula: see text] are predicted by the quasi-harmonic Debye model in a wide pressure (0–80 GPa) and temperature (0–750 K) ranges.


2009 ◽  
Vol 23 (32) ◽  
pp. 5929-5934 ◽  
Author(s):  
T. JEONG

The electronic band structure of LuPd 2 Si 2 was studied based on the density functional theory within local density approximation and fully relativistic schemes. The Lu 4f states are completely filled and have flat bands around -5.0 eV. The fully relativistic band structure scheme shows that spin–orbit coupling splits the 4f states into two manifolds, the 4f7/2 and the 4f5/2 multiplet.


2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jacky Even ◽  
Laurent Pedesseau ◽  
Eric Tea ◽  
Samy Almosni ◽  
Alain Rolland ◽  
...  

Potentialities of density functional theory (DFT) based methodologies are explored for photovoltaic materials through the modeling of the structural and optoelectronic properties of semiconductor hybrid organic-inorganic perovskites and GaAs/GaP heterostructures. They show how the properties of these bulk materials, as well as atomistic relaxations, interfaces, and electronic band-lineups in small heterostructures, can be thoroughly investigated. Some limitations of available standard DFT codes are discussed. Recent improvements able to treat many-body effects or based on density-functional perturbation theory are also reviewed in the context of issues relevant to photovoltaic technologies.


2018 ◽  
Vol 6 (2) ◽  
pp. 53
Author(s):  
Salah Daoud ◽  
Rabie Mezouar ◽  
Abdelfateh Benmakhlouf

The present work aims to investigate the structural parameters and the piezoelectric coefficients of cubic zinc-blende Aluminum phosphide (AlP) under high pressure up to 21 GPa, using plane wave-pseudopotential (PW-PP) approach in the framework of the density functional theory (DFT) and the density functional perturbation theory (DFPT) with the generalized gradient approximation (GGA) for the exchange-correlation functional. The results obtained are analyzed and compared with other data of the literature. The structural parameters and the piezoelectric coefficients calculated here agree well with other data of the literature. We found also that both the direct and converse piezoelectric coefficients increase with increasing pressure up to 21 GPa. 


2014 ◽  
Vol 925 ◽  
pp. 390-395
Author(s):  
Noureddine Amrane ◽  
Maamar Benkraouda

We present a systematic and comparative study of the electronic properties of CeX monochalcogenides, The density of state (DOS) and electronic band structure of CeX (X=S, Se, Te) have been calculated using the full-potential linearized augmented plane-wave (FP-LAPW) + local orbital (lo) method based on the density functional theory (DFT), which is implemented in WIEN2k code. The trends in the high pressure behavior of these systems are discussed. Four approximations for the exchange-correlation functional have been used, the GGA's of Perdew-Burke-Ernzherhof. (PBE08) , Engel-Vosko (EV93), a modified version of the exchange potential proposed by Becke and Johnson (MBJ), and LDA+U is used to calculate the band gaps at different pressures. All methods allow for a description of the Ce f electrons as either localized or delocalized, it is found that the underestimations of the bandgap by means of LDA-GGA and Engel-Vosko are considerably improved by using the modified Becke-Johnson (MBJ) potential for all compounds in the series, On the other hand, LDA+U, method gives good results for the lighter chalcogenides, but it fails to give good results for the heavier cerium monochalcogenides.


2008 ◽  
Vol 63 (2) ◽  
pp. 154-160 ◽  
Author(s):  
Lara Kabalan ◽  
Samir F. Matar ◽  
Mirvat Zakhour ◽  
Jean François Létarda

Ab initio computations within the density functional theory are reported for the spin cross-over complex [Fe(btz)2(NCS)2] (btz = 2.2'-bis-4.5-dihydrothiazine), where 3d6 FeII is characterized by high-spin (HS t2g4, eg2) and low-spin (LS t2g6, eg0) states. Results of infrared and Raman spectra for the isolated molecule are complemented for the crystalline solid with a full account of the electronic band structure properties: the density of states assessing the crystal field effects and the chemical bonding, assigning a specific role to the Fe-N interactions within the coordination sphere of FeII


2020 ◽  
Vol 557 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Husnu Koc ◽  
Selami Palaz ◽  
Sevket Simsek ◽  
Amirullah M. Mamedov ◽  
Ekmel Ozbay

In the present paper, we have investigated the electronic structure of some sillenites - Bi12MO20 (M = Ti, Ge, and Si) compounds based on the density functional theory. The mechanical and optical properties of Bi12MO20 have also been computed. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The band gap trend in Bi12MO20 can be understood from the nature of their electronic structures. The obtained electronic band structure for all Bi12MO20 compounds is semiconductor in nature. Similar to other oxides, there is a pronounced hybridization of electronic states between M-site cations and anions in Bi12MO20. Based on the obtained electronic structures, we further calculate the frequency-dependent dielectric function and other optical functions.


RSC Advances ◽  
2015 ◽  
Vol 5 (56) ◽  
pp. 44960-44968 ◽  
Author(s):  
A. H. Reshak

Using the density functional theory plus Hubbard Hamiltonian we have investigated the spin up/down electronic band structure, density of states, electronic charge density distribution and the dispersion of the optical properties of microcrystalline β-RbNd(MoO4)2.


Sign in / Sign up

Export Citation Format

Share Document