Electronic structure of polypyrrole composited with low percent of graphene nanofiller

2021 ◽  
Author(s):  
Zulqarnain Chaughtai ◽  
Muhammad Ali Hashmi ◽  
Muhammad Yar ◽  
Khurshid Ayub
Keyword(s):  
Electronic Structure ◽  
Theoretical Model ◽  
Theoretical Calculations ◽  
Low Concentration ◽  
Polypyrrole Composite

Low concentration of graphene (<5%) in graphene/polypyrrole composite makes it quite challenging to devise a theoretical model for such composites. Herein we present theoretical calculations for geometric electronic and optical...

scholarly journals Colossal anomalous Nernst effect in a correlated noncentrosymmetric kagome ferromagnet

2021 ◽  
Vol 7 (13) ◽  
pp. eabf1467
Author(s):  
T. Asaba ◽  
V. Ivanov ◽  
S. M. Thomas ◽  
S. Y. Savrasov ◽  
J. D. Thompson ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electronic Structure ◽  
Theoretical Calculations ◽  
Zero Magnetic Field ◽  
Nernst Effect ◽  
Nodal Lines ◽  
Transverse Response ◽  
Narrow Bands ◽  
Strong Spin ◽  
Anomalous Nernst Effect

The transverse voltage generated by a temperature gradient in a perpendicularly applied magnetic field, termed the Nernst effect, has promise for thermoelectric applications and for probing electronic structure. In magnetic materials, an anomalous Nernst effect (ANE) is possible in a zero magnetic field. We report a colossal ANE in the ferromagnetic metal UCo0.8Ru0.2Al, reaching 23 microvolts per kelvin. Uranium’s 5f electrons provide strong electronic correlations that lead to narrow bands, a known route to producing a large thermoelectric response. In addition, uranium’s strong spin-orbit coupling produces an intrinsic transverse response in this material due to the Berry curvature associated with the relativistic electronic structure. Theoretical calculations show that in UCo0.8Ru0.2Al at least 148 Weyl nodes, and two nodal lines, exist within 60 millielectron volt of the Fermi level. This work demonstrates that magnetic actinide materials can host strong Nernst and Hall responses due to their combined correlated and topological nature.

scholarly journals Effect of Electronic Correlations on the Electronic Structure, Magnetic and Optical Properties of the Ternary RCuGe Compounds with R = Tb, Dy, Ho, Er

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3536
Author(s):  
Alexey V. Lukoyanov ◽  
Lubov N. Gramateeva ◽  
Yury V. Knyazev ◽  
Yury I. Kuz’min ◽  
Sachin Gupta ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Theoretical Calculations ◽  
Rare Earth Ions ◽  
Local Spin Density Approximation ◽  
Electron Correlations ◽  
Absorption Region ◽  
Densities Of States ◽  
Interband Light Absorption ◽  
Good Agreement

In this study, the ab initio and experimental results for RCuGe ternary intermetallics were reported for R = Tb, Dy, Ho, Er. Our theoretical calculations of the electronic structure, employing local spin density approximation accounting for electron–electron correlations in the 4f shell of Tb, Dy, Ho, Er ions were carried in DFT+U method. The optical properties of the RCuGe ternary compounds were studied at a broad range of wavelengths. The spectral and electronic characteristics were obtained. The theoretical electron densities of states were taken to interpret the experimental energy dependencies of the experimental optical conductivity in the interband light–absorption region. From the band calculations, the 4f shell of the rare-earth ions was shown to provide the major contribution to the electronic structure, magnetic and optical properties of the RCuGe intermetallics. The accounting for electron–electron correlations in Tb, Dy, Ho, Er resulted in a good agreement between the calculated and experimental magnetic and optical characteristics.

Electronic structure of NixTiSe2 (0.05 ≤ x ≤ 0.46) compounds with ordered and disordered Ni

2017 ◽  
Vol 19 (6) ◽  
pp. 4500-4506 ◽  
Author(s):  
A. S. Shkvarin ◽  
Yu. M. Yarmoshenko ◽  
A. I. Merentsov ◽  
Yu. M. Zhukov ◽  
A. A. Titov ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Absorption Spectroscopy ◽  
Theoretical Calculations ◽  
Electronic States ◽  
Intercalation Compounds ◽  
X Ray ◽  
Density Of Electronic States ◽  
X Ray Absorption

The electronic structure of NixTiSe2 intercalation compounds with disordered and ordered Ni atoms is studied using photoelectron, resonant photoelectron and X-ray absorption spectroscopy, theoretical calculations of the X-ray spectra and density of electronic states.

A Simple Theoretical Model to Study the Voltage Dependence of the Electronic Structure of Phenyl Ethylene Oligomers

2003 ◽  
Vol 1006 (1) ◽  
pp. 68-81 ◽  
Author(s):  
YAMIL SIMÓN-MANSO ◽  
CARLOS GONZALEZ ◽  
VLADIMIRO MUJICA ◽  
YOSSLEN ARAY ◽  
MANUEL MARQUEZA
Keyword(s):  
Electronic Structure ◽  
Theoretical Model ◽  
Voltage Dependence ◽  
Simple Theoretical Model ◽  
Ethylene Oligomers

Molecular electronic structure of subphthalocyanine macrocycles

2000 ◽  
Vol 04 (06) ◽  
pp. 611-620 ◽  
Author(s):  
V. R. FERRO ◽  
L. A. POVEDA ◽  
R. H. GONZÁLEZ-JONTE ◽  
J. M. GARCIA DE LA VEGA ◽  
T. TORRES ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Central Region ◽  
Quantum Chemical ◽  
Theoretical Calculations ◽  
Molecular Electronic ◽  
X Ray ◽  
Compositional Changes ◽  
Molecular Electronic Structure ◽  
Semiempirical Mndo

Quantum chemical calculations at semiempirical (MNDO methods) and ab initio (6-31G and STO-3G basis ses) levels have been performed on boron(III) subphthalocyanines 1-10. Theoretical calculations predict a cone-shaped structure for these compounds independently of the kind of peripheral substitution and even of compositional changes in the central region of the macrocycle (for example, substitution of the boron atom by two hydrogens). The theoretical calculations are in excellent agreement with previous X-ray determinations.

The electronic structure and superexchange interactions in transition-metal compounds

1987 ◽  
Vol 65 (10) ◽  
pp. 1262-1271 ◽  
Author(s):  
J. Zaanen ◽  
G. A. Sawatzky
Keyword(s):  
Electronic Structure ◽  
Charge Transfer ◽  
Transition Metal ◽  
Theoretical Calculations ◽  
Transition Metal Compounds ◽  
Band Gaps ◽  
Transfer Energy ◽  
Metal Compounds ◽  
Comparison With Experiment ◽  
Charge Transfer Energy

In this paper, we discuss the electronic structure of transition-metal compounds in light of a new theoretical approach using an Anderson impurity Hamiltonian. We arrive at conclusions concerning the magnitude of parameters such as the d–d Coulomb interaction (U) and the charge-transfer energy (Δ) for the transition-metal monoxides, based on theoretical calculations of the band gaps, the optical spectra, photoelectron and inverse-photoelectron spectral shapes, and comparison with experiment. We find that both Δ and U are large but comparable in magnitude.We discuss the implications for superexchange interactions and show that the observed trends in the Néel temperatures are now well described, whereas the traditional Anderson approach gave a qualitatively different trend.

scholarly journals Discovery of Two Families of Vsb-Based Compounds with V-Kagome Lattice

2021 ◽  
Vol 38 (12) ◽  
pp. 127102
Author(s):  
Yuxin Yang ◽  
Wenhui Fan ◽  
Qinghua Zhang ◽  
Zhaoxu Chen ◽  
Xu Chen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Theoretical Calculations ◽  
Photoemission Spectroscopy ◽  
Two Dimensional ◽  
Kagome Lattice ◽  
Space Group ◽  
Kagomé Lattice ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Nonmagnetic Metals

We report the structure and physical properties of two newly discovered compounds AV8Sb12 and AV6Sb6 (A = Cs, Rb), which have C 2 (space group: Cmmm) and C 3 (space group: R 3 ¯ m ) symmetry, respectively. The basic V-kagome unit appears in both compounds, but stacking differently. A V2Sb2 layer is sandwiched between two V3Sb5 layers in AV8Sb12, altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to orthorhombic. In AV6Sb6, the building block is a more complex slab made up of two half-V3Sb5 layers that are intercalated by Cs cations along the c-axis. Transport property measurements demonstrate that both compounds are nonmagnetic metals, with carrier concentrations at around 1021 cm−3. No superconductivity has been observed in CsV8Sb12 above 0.3 K under in situ pressure up to 46 GPa. Compared to CsV3Sb5, theoretical calculations and angle-resolved photoemission spectroscopy reveal a quasi-two-dimensional electronic structure in CsV8Sb12 with C 2 symmetry and no van Hove singularities near the Fermi level. Our findings will stimulate more research into V-based kagome quantum materials.

scholarly journals Infiltration Kinetics of Cr3C2 by Manganese Cupronickel in the Process of Obtaining Cermets

2015 ◽  
Vol 16 (2) ◽  
pp. 408-412
Author(s):  
T.A. Shihab ◽  
Yu.I. Paraiko ◽  
P.M. Prysyazhnyuk ◽  
L. Ya. Ropyak ◽  
V.V. Turluch ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Theoretical Calculations ◽  
Pressureless Infiltration ◽  
Lambert Function ◽  
Melt Infiltration ◽  
Height Dependence ◽  
Average Size ◽  
Kinetics Of ◽  
Carbide Particles

A theoretical model of infiltration kinetics based on the Darcy's law which was evaluated by W − Lambert function has been established for Cu-Ni-Mn alloy (grade MNMts 60-20-20) during melt infiltration into Cr3C2  porous skeletons with different morphology. It is shown, that theoretical calculations are in good correlation with experimental data obtained by pressureless infiltration of carbide preforms with open porosity 20-40 vol. % at 1200 °C. Calculations shows that infiltration height dependence on the average size of carbide particles is described by curves with a maximum which corresponds to~ 60 μm for specified system with carbide skeleton porosity of 40 vol. %.

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