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1
Content available remote

Electronic and optical properties of ZnSxSe1−x alloys

100%
Feng Z., Hu H., Cui S.
Open Physics
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2009
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vol. 7
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issue 2
340-344
EN
A series of calculations from first principles have been carried out to study structural, electronic, and optical properties of ZnSxSe1−x alloys. Our results show that the lattice constant scales linearly with sulfur composition. The imaginary parts of the dielectric function are calculated, which are in good agreement with the experimental data. We have also interpreted the origin of the spectral peaks on the basis of band structure and density of states. Additionally, we find that no bowing effect in the absorption edge is observed, unlike other II-VI semiconductor alloys.
2
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Aromatic λ3 heterocycles XIV. Fosfinine-ether macrocyclesheterocycles XIV. Fosfinine-ether macrocycles

100%
Pacureanu L., Mracec M.
Open Chemistry
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2005
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vol. 3
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issue 1
174-187
EN
The geometry and electronic structure of several phosphinine-ether macrocycles were investigated at semiempirical level. The calculated geometries are in good agreement with experimental data. Compared to phosphinine, the coordinative abilities of phosphinineether macrocycles based on energy considerations suggest a little lowered π acceptor character, while π donor character is improved. The molecular environment causes a significant mixing of phosphinine and phenyl substituent π levels. The geometry and electronic properties of phosphinine-ether macrocycles can provide significant host coordination properties for guest species.
3
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First-principles study of electronic and optical properties of BaS, BaSe and BaTe

100%
Feng Z., Hu H., Lv Z., Cui S.
Open Physics
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2010
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vol. 8
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issue 5
782-788
EN
The optimized crystal structure, energy band structures, density of states (DOS) and optical properties of BaX (X=S, Se and Te) were investigated by the full potential linearized augmented plane wave plus local orbitals method (FP-LAPW+lo). The exchange-correlation potential was treated using the generalized gradient approximation (GGA). We have used also Engel and Vosko GGA (EV-GGA) formalism to improve the band gap results. The calculated results such as band gaps, dielectric constants and reflectivity spectra showed good agreement with the experimental data. The effect of the spin-orbit coupling (SOC) on the optical properties was also studied and found to be very small, especially in the low-energy region.
4
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First Principle Investigations on Electronic, Magnetic, Thermodynamic, and Transport Properties of TlGdX₂ (X = S, Se, Te)

100%
Gautam R., Kumar A., Singh R.
Acta Physica Polonica A
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2017
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vol. 132
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issue 4
1371-1378
EN
In the present research paper, we investigated spin polarized electronic, magnetic, thermodynamic, and transport properties of thallium gadolinium dichalcogenides TlGdX₂ (X = S, Se, Te) using density functional theory. Electronic structure reveals that all the three compounds are wide band gap semiconductors which are beneficial for good thermoelectric performance. Calculated magnetic moment of TlGdX₂ is found to be in good agreement with available experimental values and mainly dominant by Gd³⁺ ions. Semiclassical Boltzmann transport theory has been used to calculate the Seebeck coefficient and electrical conductivity for the proposed dichalcogenides. Calculated values of the Seebeck coefficient and electrical conductivity are found to be consistent with available experimental values in literature. Thermodynamic properties of TlGdX₂ have also been estimated for the first time and explained on the basic facts.
5
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Pressure Effects on Structural, Electronic, Elastic, and Optical Properties of Cubic and Tetragonal Phases of BaZrO_{3}

100%
Yang X., Wang Y., Song Q., Chen Y., Hong Xue Y.
Acta Physica Polonica A
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2018
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vol. 133
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issue 5
1138-1143
EN
A recent experimental study found the phase transition from cubic to tetragonal phase at 17.2 GPa in BaZrO_{3}. In this paper, we investigate the structural, electronic, elastic, and optical properties of BaZrO_{3} in the cubic and tetragonal structures under pressure by using first-principle density-functional theory. The main results are summarized as follows: (1) An indirect band structure is displayed for both cubic and tetragonal phases. The band gap increases by ~1 eV as a result of the phase transition. (2) The elastic constants C_{ij}'s indicate that the cubic and tetragonal phases are mechanically stable. The easiest deformation mechanism in both phases is the shear along the (100) plane. (3) The real and imaginary parts of dielectric function for the cubic and tetragonal phases shift towards higher energies with pressure. Our results are in agreement with the available experimental and prior theoretical data.
6
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Few-electron semiconductor quantum dots with Gaussian confinement

100%
Gomez S., Romero R.
Open Physics
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2009
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vol. 7
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issue 1
12-21
EN
We have performed Hartree-Fock calculations of the electronic structure of N ≤ 10 electrons in a quantum dot modeled with a confining Gaussian potential well. We discuss the conditions for the stability of N bound electrons in the system. We show that the most relevant parameter determining the number of bound electrons is V 0 R 2. Such a feature arises from widely valid scaling properties of the confining potential. Gaussian Quantum dots having N = 2, 5, and 8 electrons are particularly stable in agreement with the Hund rule. The shell structure becomes less and less noticeable as the well radius increases.
7
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DFT study on electronic structures and optical absorption properties of C, S cation- doped SrTiO3

100%
Liu J., Wang L., Liu J., Wang T., Qu W., Li Z.
Open Physics
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2009
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vol. 7
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issue 4
762-767
EN
The effects of C cation and S cation doping on the electronic structures and optical properties of SrTiO3 are investigated by density function theory (DFT) calculations. The calculated results reveal that the top of the valence band is predominately made up of the O 2p states for the pure SrTiO3. When SrTiO3 was doped with C cation and S cation, the top of the valence bands consists mainly of O 2p+C 2s hybrid orbitals and O 2p+S 3s hybrid orbitals, respectively. The band gap of SrTiO3 is narrowed by the doping with C cation and S cation, especially for the C and S-codoped SrTiO3. Moreover, the red shifts of the absorption edge are found by the calculated optical properties, which is consistent with reported experiment results. It is the explanation for their visible light respondency by the presence of C 2s and S 3s states on the upper edge of the valence band. All of these results can explain the good photocatalytic properties of C, S cation-codoped SrTiO3 under visible light irradiation.
8
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First-principle calculations for electronic structure and bonding properties in layered Na2Ti3O7

100%
An Y., Li Z., Xiang H., Huang Y., Shen J.
Open Physics
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2011
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vol. 9
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issue 6
1488-1492
EN
First-principles calculations of Na2Ti3O7 have been carried out with density-functional theory (DFT) and ultrasoft pseudopotentials. The electronic structure and bonding properties in layered Na2Ti3O7 have been studied through calculating band structure, density of states, electron density, electron density difference and Mulliken bond populations. The calculated results reveal that Na2Ti3O7 is a semiconductor with an indirect gap and exhibits both ionic and covalent characters. The stability of the (Ti3O7)2− layers is attributed to the covalent bonding of strong interactions between O 2p and Ti 3d orbitals. Furthermore, the O atoms located in the innerlayers interact more strongly with the neighboring Ti atoms than those in the interlayer regions. The ion-exchange property is due to the ionic bonding between the Na+ and (Ti3O7)2− layers, which can stabilize the interlayers of layered Na2Ti3O7 structure.
9
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Band structure and optical properties of antimony-sulfobromide: density functional calculation

100%
Akkus H., Mamedov A., Kazempour A., Akbarzadeh H.
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vol. 6
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issue 1
64-75
EN
The electronic structure, linear, and non-linear optical properties of ferroelectric-semiconductor SbSBr are investigated in the non-polar (paraelectric) and polar (ferroelectric) phase, using the density functional methods in the generalized gradient approximation. The electronic band structure obtained shows that SbSBr has an indirect forbidden gap of 2.16 and 2.21 eV in the paraelectric and ferroelectric phase, respectively. The linear photon-energy dependent dielectric functions and some optical functions, such as absorption and extinction coefficients, refractive index, energy-loss function, reflectivity, and optical conductivity in both phases and photon-energy dependent second-order susceptibilities in the ferroelectric phase are calculated. Moreover, some important optical parameters, such as the effective number of valence electrons and the effective optical dielectric constant, are calculated in both phases.
10
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Under Pressure DFT Investigations on Optical and Electronic Properties of PbZrO₃

100%
Nazir G., Tariq S., Afaq A., Mahmood Q., Saad S., Mahmood A., Tariq S.
Acta Physica Polonica A
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2018
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vol. 133
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issue 1
105-113
EN
In this article, density functional theory has been used to investigate the structural and optoelectronic properties of PbZrO₃ (PZO) under pressure from 0 to 350 GPa. In order to achieve ground state structural stability, generalized gradient approximations has been utilized. By studying electronic properties, indirect band-gap nature of PZO appears to change at 15 GPa to direct band-gap. Optical analysis include under pressure responses of real and imaginary parts of dielectric function, optical conductivity, optical absorption coefficient, energy loss function, refractive index, reflectivity and extinction coefficient. Most of the results have been found to be consistent with literature. Study reveals that static dielectric constant and band-gap are in accordance with the Penn model which validates our computed results. Moreover, static dielectric constant and static refractive index directly increases with pressure. Material preserves its positive value of refractive index at all pressures and therefore, it is not a negative index metamaterial. Plasma frequency increases directly with pressure that destabilize the under study material. Our results could be very useful for developing novel optoelectronic devices based on PZO suitable to work under extreme conditions.
11
Content available remote

First principles study of electronic and optical properties of InAs

100%
Feng Z., Hu H., Cui S., Wang W., Lu C.
Open Physics
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2009
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vol. 7
|
issue 4
786-790
EN
The electronic and optical properties of InAs in core-level spectra are calculated using the full-potential linearized augmented plane wave plus local orbitials (FP-LAPW +lo) method. The real and imaginary parts of the dielectric function ε(ω), the optical absorption coefficient I(ω), the reflectivity R(ω), the refractive index n(ω), and the extinction coefficient k(ω)are calculated. All these values are in good agreement with the experimental data. The effect of spin-orbit coupling on optical properties is also investigated and found to be quite small.
12
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First-principles studies of the electronic structure and optical properties of AgBO3 (B=Nb,Ta) in the paraelectric phase

100%
Cabuk S., Simsek S.
|
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vol. 6
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issue 3
730-736
EN
The electronic energy-band structure, density of states (DOS), and optical properties of AgBO3 in the paraelectric cubic phase have been studied by using density functional theory within the local density approximation for exchange-correlation for the first time. The band structure shows a band gap of 1.533 eV (AgNbO3)and 1.537 eV (AgTaO3)at (M-⌈)point in the Brillouin zone. The optical spectra of AgBO3 in the photon energy range up to 30 eV are investigated under the scissor approximation. The real and imaginary parts of the dielectric function and - thus the optical constants such as reflectivity, absorption coefficient, electron energy-loss function, refractive index, and extinction coefficient - are calculated. We have also made some comparisons with related experimental and theoretical data that is available.
13
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Theoretical study of NO3− interacting with carbon nanotube

100%
Guerini S., Azevedo D., Lima M., Zanella I., Filho J.
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vol. 6
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issue 1
105-108
EN
This paper deals with quantum mechanical interaction of no 3− with (5,5) and (8,0) swcnts. To perform this we have made an ab initio calculation based on the density functional theory. In these framework the electronic density plays a central role and it was obtained of a self-consistent field form. It was observed through binding energy that NO3− molecule interacts with each nanotube in a physisorption regime. We propose these swcnts as a potential filter device due to reasonable interaction with NO3− molecule. Besides this type of filter could be reusable, therefore after the filtering, the swcnts could be separated from NO3− molecule.
14
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Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

88%
Kaczmarzyk T., Rutkowska I., Dziliński K.
Nukleonika
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2015
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vol. 60
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issue 1
51-55
EN
Molecular and electronic structure changes during successive reduction of a Fe-tetraphenylporphyrin chloride [Fe(III)(TPP):Cl] complex are reported on the basis of Mössbauer spectroscopy and DFT calculations. It is established that the attachment of additional electrons to a neutral Fe(III)(TPP):Cl molecule leads to significant shortening of Fe-N distances at the first stage of the reduction Fe(III)(TPP):Cl → Fe(II)(TPP) and lengthening of these bonds at the second stage Fe(II)(TPP) → Fe(I)(TPP). Changes of other bond lengths of the porphyrin ring also appear but in less degree. Interaction of Fe(II) and Fe(I)(TPP) with tetrahydrofuran (THF) solvent is considered. Electron configuration of Fe(II)(TPP) corresponds to intermediate-spin (S = 1) state and in the case of Fe(I)(TPP) low-spin state (S = ½) is observed. Electron density distribution in Fe(II)- and Fe(I)(TPP) complexes, in association with Mössbauer data, is analyzed. Good correlation between experimental and theoretical results was obtained.
15
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First-principles LCAO study of phonons in NiWO4

88%
Kuzmin A., Kalinko A., Evarestov R.
Open Physics
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2011
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vol. 9
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issue 2
502-509
EN
The electronic, structural and phonon properties of antiferromagnetic wolframite-type NiWO4 have been studied using first-principles spin-polarized LCAO calculations based on the hybrid Hartree-Fock (HF)/density functional (DFT) scheme. The influence of different percentages of HF contribution, i.e. different correlation strength, on the structure and phonon frequencies has been investigated and compared with the available experimental data.
16
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A first-principles study of π-conjugated thiol phenothiazine derivatives adsorbed on Au(111) surface

88%
Morari C., Bogdan D., Turcu I.
Open Physics
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2009
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vol. 7
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issue 2
332-339
EN
We present an extensive theoretical study of a series of phenothiazine derivatives adsorbed on Au(111). A series of experimentally accessible quantities are calculated (ultra-violet photoemission spectra, scanning tunneling microscopy images). All simulations were performed by using DFT techniques and LCAO expansion of the molecular orbitals. The microscopic picture established in this work provides a deeper understanding of the interfacial processes that govern the working principle of single-molecule electronics and organic electronic devices.
17
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Possible schemes of photoassociation processes in the KLi molecule with newly calculated potential energy curves

88%
Miądowicz Ł., Jasik P., Sienkiewicz J.
|
EN
We present four promising schemes for photoassociative formation of KLi molecule in its ground electronic state. Analysis is based on newly calculated adiabatic potentials supported by transition dipole moments and Franck-Condon factors.
18
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First-principles study of electronic structure and optical properties of Sr(Ti,Zr)O3

88%
Celik G., Cabuk S.
Open Physics
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2013
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vol. 11
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issue 3
387-393
EN
Electronic and optical properties of Sr(Ti,Zr)O3 crystals in the cubic (Pm-3m) and tetragonal (I4/mcm) phase were calculated by the first-principles calculations using the density functional theory and the local density approximation. The band structure of cubic and tetragonal phases show an indirect band gap at (R-Γ) point and at (M-Γ) point in the Brillouin zone, respectively. The linear photon-energy dependent dielectric functions and some optical properties such as the absorption coefficient, energy-loss function and reflectivity are calculated for both phases. The optical properties of tetragonal phase of Sr(Ti,Zr)O3 were investigated by theoretical methods for the first time. We have also made some comparisons with the available related experimental and theoretical data.
19
Content available remote

First-Principles Calculations for Structural, Elastic, Electronic and Thermodynamic Properties of HfZn_{2} under Pressure

88%
Li G.-J., Shi L.-T., Hu C.-E., Cheng Y., Ji G.-F.
Acta Physica Polonica A
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2018
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vol. 133
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issue 5
1299-1306
EN
By using density functional theory within the Perdew-Burke-Ernzerhof generalized gradient approximation implemented in the VASP code, we study the structural, elastic, electronic, and thermodynamic properties of C15 Laves-phase compound HfZn_{2}. Comparing the lattice constants calculated from the Perdew-Burke-Ernzerhof generalized gradient approximation and local density approximation, we find that the former is in better agreement with the experimental data. The elastic constants of HfZn_{2} calculated by strain-stress method indicate that they keep stable up to 100 GPa. The bonding characteristics are discussed by analyzing the energy band structure, charge density distribution and charge density difference. Phonon dispersion curves and phonon density of states of HfZn_{2} at the different pressure are predicted for the first time. In addition, there is no imaginary frequency in the phonon band at different pressure, which also shows that HfZn_{2} is stable up to 100 GPa. Vibrational models are also illustrated based on phonon and group theory. The thermodynamic properties under high temperature and high pressure are calculated by different thermodynamic models. The heat capacity at constant pressure and low temperature calculated by quasi-harmonic approximation is more close to the measurement than that calculated by quasi-harmonic Debye models.
20
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First-principles investigation of structural, electronic, optical and dynamical properties in CsAu

88%
Erdinc B., Soyalp F., Akkus H.
Open Physics
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2011
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vol. 9
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issue 5
1315-1320
EN
The structural, electronic, optical and dynamical properties of CsAu compound in the CsCl(B2) phase were investigated using the density functional theory (DFT) within the generalized gradient approximation (GGA). The calculated lattice constant, static bulk modulus and first-order pressure derivative of the bulk modulus are reported and compared with previous experimental and theoretical calculations. The calculated electronic band structure for this compound is in good agreement with available theoretical and experimental studies. The present band calculation indicates that CsAu compound has an indirect gap at R→X points. Furthermore, the linear photon-energy-dependent dielectric functions have been calculated. For the first time, the electronic structure results are used, within the implementation of a linear-response technique, for calculations of phonon properties.
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