AB INITIO INVESTIGATION OF ELECTRONIC AND VIBRATIONAL PROPERTIES OF ZnS AND ZnSe CRYSTALS BY DIFFERENT XC-FUNCTIONALS

2009 ◽  
Vol 23 (19) ◽  
pp. 3845-3857 ◽  
Author(s):  
D. M. POPOVA ◽  
B. N. MAVRIN ◽  
A. V. SOLOV'YOV
Keyword(s):  
First Principles ◽  
Correlation Energy ◽  
Quantitative Description ◽  
Basis Set ◽  
Vibrational Properties ◽  
Hybrid Functional ◽  
Exchange Correlation ◽  
Zinc Blende ◽  
Dependent Potential ◽  
Projector Augmented Wave

Ground state properties of zinc-blende structures ZnS and ZnSe are investigated from first principles using plane wave basis, projector augmented wave method and local orbital-dependent potential, as well as a basis set of Gaussian-type functions with hybrid functionals for the approximation of exchange-correlation energy. The results of DFT calculations with the LDA, LDA+U, GGA, GGA+U, BLYP, B3P86, P3PW, BH-HP, KMLYP and B3LYP approximations are compared. It is shown that the hybrid functional B3LYP provides an accurate quantitative description of the structural, electronic and vibrational properties of ZnS and ZnSe in comparison with experimental data.

THE FIRST-PRINCIPLES STABILITY STUDY OF PdC AND CdC COMPOUNDS

2013 ◽  
Vol 27 (06) ◽  
pp. 1350016
Author(s):  
ENGIN ATESER ◽  
HAVVA BOGAZ OZISIK ◽  
ENGIN DELIGOZ ◽  
KEMAL COLAKOGLU
Keyword(s):  
First Principles ◽  
Elastic Moduli ◽  
Stability Study ◽  
Correlation Effects ◽  
Generalized Gradient ◽  
Shear Moduli ◽  
Exchange Correlation ◽  
Zinc Blende ◽  
Debye Temperatures ◽  
Stable Structures

We have studied structural, mechanical and dynamical properties of PdC and CdC compounds to predict the most stable structure. We have focused on seven binary structure types as rock salt (RS), caesium chloride ( CsCl ), zinc blende (ZB), wurtzite (WZ), tungsten carbide (WC), cadmium telluride ( CdTe ) and nickel arsenide ( NiAs ). For modelling exchange-correlation effects we have used generalized gradient (GGA) approximation based on Perdew–Burke–Ernzhorf functional (PBE). The polycrystalline elastic moduli such as Young's and shear moduli, Poisson's ratio, sound velocities, Debye temperatures and shear anisotropic factors have been presented for mechanically stable structures using second-order elastic constants calculated from the stress-strain relations. The results show that PdC is thermodynamically, mechanically and dynamically stable in ZB structure. On the other hand, while CdC is energetically in favor of RS structure, it is mechanically and dynamically stable in ZB structure.

First-Principles Study of Hydrogen Storage in Fe-Ti System

2015 ◽  
Vol 365 ◽  
pp. 266-271
Author(s):  
Ahlem Khadraoui ◽  
Fatima Zohra Bentayeb
Keyword(s):  
Hydrogen Storage ◽  
First Principles ◽  
Real Space ◽  
Basis Set ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Correlation Potential ◽  
Energy Cutoff ◽  
Bonding Properties ◽  
Pseudo Potential

In this study, a first-principles investigation of hydrogen storage in the FeTi intermetallic is carried out. The structural and electronic changes due to hydrogen insertion into the FeTi intermetallic are determined using DFT and pseudo-potential calculations through the code SIESTA (Spanish Initiative for Electronic Simulation of Thousand of Atoms). The pseudopotentials are constructed using Troullier and Martins parametrization which describes correctly the ion-electron interactions. To define the real-space grid, necessary for numerical calculations of the electron density, detailed tests were performed in order to choose the appropriate basis set, the energy cutoff and the k-grid cutoff. The exchange-correlation potential is treated with the generalized gradient approximation (GGA). Lattice data, bonding properties and the density of states provide an explanation for the role played by hydrogen in the chemical bond with the Ti and Fe constituents.

Exchange correlation energy as a function of the orbital occupancies: Implementation on first principles local orbital methods

2002 ◽  
Vol 91 (2) ◽  
pp. 151-156 ◽  
Author(s):  
P. Pou ◽  
R. Oszwałdowski ◽  
H. Vázquez ◽  
R. Pérez ◽  
F. Flores ◽  
...  
Keyword(s):  
First Principles ◽  
Correlation Energy ◽  
Exchange Correlation

scholarly journals Calibration of 57Fe Mössbauer constants by first principles

2016 ◽  
Vol 18 (15) ◽  
pp. 10201-10206 ◽  
Author(s):  
Silvia Casassa ◽  
Anna Maria Ferrari
Keyword(s):  
Isomer Shift ◽  
Ab Initio ◽  
First Principles ◽  
Functional Approach ◽  
Basis Set ◽  
Hybrid Functional ◽  
57Fe Mössbauer ◽  
Mössbauer Isomer Shift ◽  
Quadrupolar Moment

Ab initio periodic esimate of Mössbauer isomer shift and quadrupolar moment for iron: hybrid functional approach in a GTO basis set.

First-principles investigation of the vibrational properties of 3-tert-butylcyclohexene

Open Physics ◽  
2010 ◽  
Vol 8 (5) ◽  
Author(s):  
Katalin Gaál-Nagy
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Vibrational Properties ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Density Functional Perturbation Theory ◽  
Characteristic Modes ◽  
Correlation Potential

AbstractI present a first-principles investigation of the vibrational properties of the chiral molecule 3-tert-butylcyclohexene. The vibrational density of states (vDOS) of the two existing conformers has been calculated ab initio within the framework of density-functional theory and density-functional perturbation theory, using both the local-density approximation and the generalized-gradient approximation for the exchange-correlation potential. The vDOS of the two conformers are very similar. The vDOS has been investigated with respect to contributions of the cyclohexene ring and the tert-butyl group and also regarding the localization of vibrational modes. Additionally, the eigendisplacements of characteristic modes of 3-tert-butylcyclohexene have been analyzed.

scholarly journals Revisiting the Zinc-Blende/Wurtzite Heterocrystalline Structure in CdS

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Zhaohui Zhou ◽  
Mingtao Li ◽  
Po Wu ◽  
Liejin Guo
Keyword(s):  
Correlation Energy ◽  
Local Density ◽  
Energy Functional ◽  
Band Alignment ◽  
Band Offset ◽  
Type I ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Zinc Blende ◽  
Interface Location

The band offset at CdS zinc-blende (ZB)/wurtzite (WZ) heterocrystalline interface was revisited using the first principles calculations with the local density approximation (LDA), generalized gradient approximation (GGA), and Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. It was revealed that, unlike most IV, III-V, and II-VI semiconductors, the band alignment at CdS ZB/WZ heterocrystalline interface was of type-I with straddling lineup of band edges, which was irrespective of the exchange-correlation energy functional, the thickness of ZB and WZ segments, and the ZB/WZ interface location. The partial charge densities of VBM and CBM states were separated around two adjacent interfaces in one unit cell of heterocrystalline superlattice. This type of carrier localization was mainly attributed to the spontaneous polarization occurring in the WZ segment rather than the band offset at the interface.

Study of structural and electronic properties of (ZnSeZB)m/(ZnSeWZ)n superlattices based on HSE hybrid functional

2019 ◽  
Vol 33 (23) ◽  
pp. 1950269
Author(s):  
Jia-Hong Lin ◽  
Xiong-Tao Yang ◽  
Bing-Suo Zou ◽  
Li-Jie Shi
Keyword(s):  
Solar Energy ◽  
Electronic Properties ◽  
First Principles ◽  
Band Alignment ◽  
Good Prediction ◽  
Type Ii ◽  
Carrier Localization ◽  
Hybrid Functional ◽  
Zinc Blende ◽  
Structural And Electronic Properties

Using first-principles method, we studied systematically the structural and electronic properties of ZB/WZ superlattices of ZnSe. The band offsets are calculated by Heyd–Scuseria–Ernzerhof (HSE) hybrid functional which can give a good prediction on the relative band positions. The band alignment at ZB/WZ interface is found to be type-II with holes localized in wurtzite region and electrons in zinc-blende region, which is suitable for optoelectronic and solar energy conversion. The origin of type-II character and the carrier localization are investigated in detail.

Electronic exchange-correlation, many-body effect issues on first-principles calculations of bulk SiC polytypes

2018 ◽  
Vol 32 (29) ◽  
pp. 1850328
Author(s):  
Kamel Demmouche ◽  
José Coutinho
Keyword(s):  
Dielectric Properties ◽  
Band Structure ◽  
First Principles ◽  
Basis Set ◽  
High Symmetry ◽  
Many Body ◽  
Exchange Correlation ◽  
Phonon Band ◽  
Many Body Effects ◽  
Good Agreement

The first-principles Projector-Augmented Wave method (PAW) is used to investigate the electronic, phonon band structure and dielectric properties of four bulk silicon carbide (SiC) polytypes. We employ PAW pseudopotential density functional theory with Perdew, Burke and Ernzerhof (PBE) and hybrid HSE06 approximations of the exchange-correlation functional. Many-body effects are incorporated using the GW approximation of the self-interaction to study SiC properties. GW method in its single-shot variant, which is based on the many-body perturbation theory (MBPT), is used to calculate the quasi-particle (QP) energies of the band structure and the dielectric properties for different polytypes. The electronic band structure determination within GW method uses the Wannier procedure where a basis set of maximally localized Wannier function (MLWF) is constructed to interpolate the QP energies of few regular mesh k-points to the high-symmetry lines in Brillouin zone. As a consequence of QP correction to the Kohn–Sham energies, bandgap is increased by upto 3 eV in case of 4H–SiC, as compared to PBE bandgap. GW results are comparable to those of hybrid functionals and are in good agreement with the experimental results. The optical properties are then studied within PBE, HSE06 and include many-body effects. In addition, the phonon band structure has been investigated within HSE06 and compared to previous PBE results. We found good agreement with the previous theoretical results and the experimental available data.

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