First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

First Principles Calculations on Cu-Doped TiO2

2015 ◽  
Vol 1101 ◽  
pp. 70-74 ◽  
Author(s):  
Waqas Mahmood
Keyword(s):  
Optical Properties ◽  
Plane Wave ◽  
First Principles ◽  
Geometry Optimization ◽  
Titanium Atom ◽  
Mesh Size ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Cutoff Energy

The electronic and optical properties of tetragonal rutile TiO2 are investigated by first principles calculations using plane-wave pseudopotentials. Generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (GGA-PBE) is employed with Vanderbilt’s ultrasoft pseudopotentials (USPs) for the geometry optimization. The cutoff energy 380 eV and Monkhorst-Pack (MP) grid of size 5 x 5 x 8 is used to study the electronic properties of TiO2. Besides, the optical properties of TiO2 are studied using a mesh size of 9 x 9 x 9. A periodic supercell of size 2a x 2b x 2c is created and a single Copper (Cu) atom directly substitutes the titanium atom. The geometry is optimized at cutoff energy 440 eV with MP grid of size 3 x 3 x 8 and a denser k-points mesh of size 6 x 6 x 6 is used for the investigation of optical properties.

scholarly journals Electron–phonon scattering and excitonic effects in T-carbon

RSC Advances ◽  
2020 ◽  
Vol 10 (41) ◽  
pp. 24515-24520 ◽  
Author(s):  
Xiangtian Bu ◽  
Shudong Wang
Keyword(s):  
Optical Properties ◽  
Perturbation Theory ◽  
First Principles ◽  
Phonon Scattering ◽  
First Principles Calculations ◽  
Many Body ◽  
Many Body Perturbation Theory ◽  
Excitonic Effects ◽  
Electron Phonon Scattering

Through first-principles calculations combining many-body perturbation theory, we investigate electron–phonon scattering and optical properties including the excitonic effects of T-carbon.

scholarly journals First principles many-body calculations of electronic structure and optical properties of SiC nanoribbons

2016 ◽  
Vol 49 (10) ◽  
pp. 105306 ◽  
Author(s):  
Naresh Alaal ◽  
Vaideesh Loganathan ◽  
Nikhil Medhekar ◽  
Alok Shukla
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Many Body

Optical Properties and Electronic Structure of LaNi5-XCux (x=0–1.2) Intermetallic System

2010 ◽  
Vol 168-169 ◽  
pp. 529-532 ◽  
Author(s):  
Yu.V. Knyazev ◽  
Y.I. Kuz’min ◽  
A.V. Lukoyanov ◽  
Anatoly G. Kuchin
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Optical Conductivity ◽  
Theoretical Calculations ◽  
Generalized Gradient ◽  
Broad Absorption ◽  
Generalized Gradient Approximation ◽  
Electron Transitions ◽  
Intermetallic System ◽  
Conductivity Spectra

Optical properties of the LaNi5-xCux (x = 0, 0.6, 1, 1.2) compounds were studied. It was shown that substitution of copper for nickel led to noticeable changes in the optical conductivity spectra. Calculations of the electronic structure of compounds with x = 0, 1, 2 were performed using a generalized gradient approximation. The interband optical conductivity of these intermetallics was calculated. The optical ellipsometrical measurements and theoretical calculations testify to the appearance of a broad absorption structure associated with the Cu 3d  Ni 3d electron transitions and increasing with the growth of copper content.

First-principles study of electronic and optical properties of Sr2ZnN2 under pressure

2016 ◽  
Vol 30 (10) ◽  
pp. 1650139
Author(s):  
Kai Liang ◽  
Hui Zhao
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Electronic Structure ◽  
Dielectric Function ◽  
First Principles ◽  
Density Functional ◽  
Optical Transition ◽  
Dft Method ◽  
Structural Parameter ◽  
Generalized Gradient

First-principles calculations of ternary Sr2ZnN2 compound using density-functional theory (DFT) method within the generalized gradient approximation (GGA) has been performed. Based on the optimized structural parameter, the electronic properties and optical properties have been researched. The calculated lattice constants are in agreement with the experimental and theoretical results. The electronic structure have been investigated throughout the calculated band structure and density of states (DOS). It shows that this compound belongs to the semiconductors with a band gap of about 0.775[Formula: see text]eV. Furthermore, in order to clarify the optical transition of this material, the optical properties such as dielectric function, absorption coefficient, reflectivity, refractive index and energy-loss function at different pressures of 0, 10 and 20[Formula: see text]GPa in the energy range 0–20[Formula: see text]eV were performed and discussed. It shows that Sr2ZnN2 is a strong anisotropy material and the imaginary part of dielectric function shifts to higher energy region as the pressure increases. The square of calculated static refractive index is equal to static dielectric function, which corresponds to the theory formula. In conclusion, pressure is a effective method to change the electronic structure and optical properties.

Optical Properties of β-Si3N4 Studied from First-Principles Method

2012 ◽  
Vol 490-495 ◽  
pp. 3253-3256 ◽  
Author(s):  
Dong Chen ◽  
Kui Yang
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Theoretical Study ◽  
Potential Method ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Near Future ◽  
Pseudo Potential ◽  
Good Agreement

A detailed theoretical study of the optical properties of β-Si3N4 has been carried out by means of first-principles calculations using the plane-wave pseudo-potential method with generalized gradient approximation for the exchange and correlation functional. The calculated maximum absorption coefficient is 312000, which is in good agreement with the other calculated result. β-Si3N4 can be used as a photo-electronic material because its absorption curve has an abrupt limit at low energy region. The light beam with the frequency of 7eV～15eV can easily traverse the β-Si3N4 crystal. For the dielectric function, the strongest peaks are located at 6.5 and 9.0eV for the real and imaginary parts, respectively. Moreover, the calculated static dielectric constant is 3.21. Actually speaking, our calculated results should be testified by experiments in the near future.

Band Structure and Optical Properties of CuInSe2

2014 ◽  
Vol 894 ◽  
pp. 254-258
Author(s):  
Rong Zhen Chen ◽  
Clas Persson
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Coupling Effect ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Generalized Gradient ◽  
Augmented Plane Wave ◽  
Generalized Gradient Approximation ◽  
Linearized Augmented Plane Wave ◽  
Good Agreement

In this work, the electronic structure and dielectric function of chalcopyrite CuInSe2 are presented. The results are based on the full-potential linearized augmented plane wave (FPLAPW) method using the generalized gradient approximation (GGA) plus an onsite Coulomb interaction U of the Cu d states. The dielectric constant, absorption coefficient and refractive index are explored by means of optical response. The spin-orbit coupling effect is considered for the calculations of electronic structure and optical properties. We find that the results based on our calculation method have good agreement compared with experimental and other earlier simulations results.

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