scholarly journals First-principles generalized gradient approximation (GGA)+Ud+Up studies of electronic structures and optical properties in cubic HfO2

2014 ◽  
Vol 81 ◽  
pp. 397-401 ◽  
Author(s):  
Jinping Li ◽  
Songhe Meng ◽  
Lingling Li ◽  
Hantao Lu ◽  
Takami Tohyama
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation

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.

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.

Thermoelectric properties of half-Heusler ZrNiPb by using first principles calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47953-47958 ◽  
Author(s):  
San-Dong Guo
Keyword(s):  
Thermoelectric Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation

We investigate the electronic structures and thermoelectric properties of a recently synthesized half-Heusler ZrNiPb compound by using a generalized gradient approximation (GGA) and GGA plus spin–orbit coupling (GGA + SOC).

First-Principles Study of Structural, Electronic and Optical Properties in BaTi0.5Ni0.5O3

2013 ◽  
Vol 834-836 ◽  
pp. 268-271
Author(s):  
Hong Liang Pan ◽  
Shi Liang Yang ◽  
Teng Li
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Absorption Spectrum ◽  
First Principles ◽  
Energy Band Structure ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Generalized Gradient Approximation ◽  
Structure Density ◽  
Pseudo Potential

The pseudo-potential plane wave (PP-PW) mehod with the generalized gradient approximation (GGA) is applied to study the electronic and optical properties of BaTi0.5Ni0.5O3. The energy band structure, density of states (DOS) are obtained. The optical properties including the dielectric function, reflectivity, absorption spectrum, extinction coefficient, energy-loss spectrum and refractive index are also calculated and analyzed in detail.

scholarly journals First Principles Study in the Electronic Structures and Optical Properties of Chalcogenide-doped AgInS2

2021 ◽  
Author(s):  
Worasak Sukkabot
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Narrow Band ◽  
Theoretical Work ◽  
Band Gaps ◽  
Generalized Gradient ◽  
Natural Properties ◽  
Se Doping ◽  
Formation Energies

Abstract The Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) is adopted to simulate the electronic structures and optical properties of AgInS2 semiconductors with S substitution by chalcogenides. The chalcogenide-doped AgInS2 semiconductor can be synthesized at the normal conditions due to the formation energies. O and Se doping in AgInS2 remain the semiconductor with the narrow band gaps, while Te doping converts semiconductor to metal. In the presence of the impurities, the contributions from p states of chalcogenides are involved, accountable for the reduction of the band gaps. Using the reflectivity and absorption coefficients, the optical properties with extensive absorption range and low reflectivity are attained by incorporating AgInS2 semiconductors with chalcogenides. Finally, this theoretical work launches a broader understanding of the absorber materials and also predicts the natural properties as the alternative for the solar cell applications.

scholarly journals Structural, Electronic, and Optical Properties of CsPb(Br1−xClx)3 Perovskite: First-Principles Study with PBE–GGA and mBJ–GGA Methods

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4944
Author(s):  
Hamid M. Ghaithan ◽  
Zeyad. A. Alahmed ◽  
Saif M. H. Qaid ◽  
Abdullah S. Aldwayyan
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Blue Shift ◽  
X Ray Diffraction ◽  
Generalized Gradient ◽  
X Ray ◽  
Electronic And Optical Properties ◽  
Generalized Gradient Approximation ◽  
Average Fraction ◽  
Experimental Values

The effect of halide composition on the structural, electronic, and optical properties of CsPb(Br1−xClx)3 perovskite was investigated in this study. When the chloride (Cl) content of x was increased, the unit cell volume decreased with a linear function. Theoretical X-ray diffraction analyses showed that the peak (at 2θ = 30.4°) shifts to a larger angle (at 2θ = 31.9°) when the average fraction of the incorporated Cl increased. The energy bandgap (Eg) was observed to increase with the increase in Cl concentration. For x = 0.00, 0.25, 0.33, 0.50, 0.66, 0.75, and 1.00, the Eg values calculated using the Perdew–Burke–Ernzerhof potential were between 1.53 and 1.93 eV, while those calculated using the modified Becke−Johnson generalized gradient approximation (mBJ–GGA) potential were between 2.23 and 2.90 eV. The Eg calculated using the mBJ–GGA method best matched the experimental values reported. The effective masses decreased with a concentration increase of Cl to 0.33 and then increased with a further increase in the concentration of Cl. Calculated photoabsorption coefficients show a blue shift of absorption at higher Cl content. The calculations indicate that CsPb(Br1−xClx)3 perovskite could be used in optical and optoelectronic devices by partly replacing bromide with chloride.

scholarly journals First Principles Study of Electronic and Optical Properties of Pristine and X (Cu, Ag And Au) Doped BiOBr

2018 ◽  
Vol 22 (2) ◽  
pp. 63-69 ◽  
Author(s):  
Samir Paudel ◽  
Puspa Raj Adhikari ◽  
Om Prakash Upadhyay ◽  
Gopi Chandra Kaphle ◽  
Anurag Srivastava
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Ab Initio Approach ◽  
Indirect Band Gap ◽  
Standard Density

The electronic structures and optical properties of pristine BiOBr and Cu, Ag and Au doped BiOBr have been analyzed by using a standard density functional theory based ab-initio approach employing generalized gradient approximation through revised Perdew Burke Ernzerhoff type parameterization. The calculation shows that both the doped and pristine BiOBr have indirect band gap, the band gap of the pristine BiOBr found 2.22eV, whereas band gap significantly reduced after doping Cu, Ag and Au on BiOBr. The band gap of Cu, Ag and Au doped BiOBr are 1.2eV, 0.9eV and 1.76eV respectively. The optical properties have been studied through dielectric function, both pure and doped BiOBr shows anisotropic nature. Journal of Institute of Science and TechnologyVolume 22, Issue 2, January 2018, page: 63-69 

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