scholarly journals Strong correlation between electronic bonding network and critical temperature in hydrogen-based superconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Belli ◽  
Trinidad Novoa ◽  
J. Contreras-García ◽  
Ion Errea
Keyword(s):  
Critical Temperature ◽  
Physical Properties ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Strong Correlation ◽  
Critical Temperatures ◽  
Structural And Electronic Properties ◽  
Superconducting Compounds ◽  
Better Than

AbstractBy analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.

STRUCTURAL AND ELECTRONIC PROPERTIES OF ONE DIMENSIONAL KxC60 CRYSTAL ENCAPSULATED IN CARBON NANOTUBE

2007 ◽  
Vol 21 (10) ◽  
pp. 1705-1714 ◽  
Author(s):  
WEI SONG ◽  
JING LU ◽  
ZHENGXIANG GAO ◽  
MING NI ◽  
LUNHUI GUAN ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
First Principles ◽  
First Principles Calculations ◽  
Single Walled Carbon Nanotube ◽  
One Dimensional ◽  
Single Walled Carbon ◽  
Structural And Electronic Properties

The structural and electronic properties of potential one dimensional (1D) superconductor — K x C 60 chain encapsulated inside a single-walled carbon nanotube is studied using first principles calculations. The stoichiometry of K to C 60 of the 1D K x C 60 crystal can reach 9, in contrast to a maximal stoichiometry of 6 found in the K doped bulk fullerides. The K 4s electrons are completely ionized, and fill chiefly the C 60-derived bands in a nonrigid way. The density of states at the Fermi level of the encapsulated 1D K x C 60 crystal is comparable to that in K doped bulk fullerides.

STRUCTURAL AND ELECTRONIC PROPERTIES OF CARBON NANOTUBES

2000 ◽  
Vol 11 (01) ◽  
pp. 175-182 ◽  
Author(s):  
ŞAKIR ERKOÇ
Keyword(s):  
Carbon Nanotubes ◽  
Electronic Properties ◽  
Molecular Mechanics ◽  
Density Of States ◽  
Linear Dependence ◽  
The Other ◽  
Tube Length ◽  
Single Wall Carbon Nanotubes ◽  
Tube Size ◽  
Structural And Electronic Properties

The structural and electronic properties of optimized open-ended single-wall carbon nanotubes with zigzag geometry have been investigated. The calculations were performed using molecular mechanics, extended Hückel, and AM1–RHF semiempirical molecular orbital methods. It has been found that the density of states of the zigzag model is sensitive to the tube size and changes as the tube length increases. On the other hand the energetics of the tube shows an almost linear dependence to the tube length, and a converging characteristics with respect to the number of hexagons forming the tube.

scholarly journals Study of Structural and Electronic Properties of Intercalated Transition Metal Dichalcogenides Compound MTiS2 (M = Cr, Mn, Fe) by Density Functional Theory

2021 ◽  
Keyword(s):  
Transition Metal ◽  
Band Structure ◽  
Electronic Properties ◽  
Density Of States ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Energy Band Structure ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Metal Dichalcogenides

In the present work, we have studied intercalated Transition Metal Dichalcogenides (TMDC) MTiS2 compounds (M = Cr, Mn, Fe) by Density Functional Theory (DFT) with Generalized Gradient Approximation (GGA). We have computed the structural and electronic properties by using first principle method in QUANTUM ESPRESSO computational code with an ultra-soft pseudopotential. A guest 3d transition metal M (viz; Cr, Mn, Fe) can be easily intercalated in pure transition metal dichalcogenides compound like TiS2. In the present work, the structural optimization, electronic properties like the energy band structure, density of states (DoS), partial or projected density of states (PDoS) and total density of states (TDoS) are reported. The energy band structure of MTiS2 compound has been found overlapping energy bands in the Fermi region. We conclude that the TiS2 intercalated compound has a small band gap while the doped compound with guest 3d-atom has metallic behavior as shown form its overlapped band structure.

About the Metal-Insulator Transition in Quasicrystals

2000 ◽  
Vol 643 ◽  
Author(s):  
J. Delahaye ◽  
C. Berger ◽  
T. Grenet ◽  
G. Fourcaudot
Keyword(s):  
Magnetic Field ◽  
Fermi Level ◽  
Electronic Properties ◽  
Field Dependence ◽  
Density Of States ◽  
Disordered Systems ◽  
Magnetic Field Dependence ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Mi Transition

AbstractElectronic properties (conductivity and density of states) of quasicrystals present strong similarities with disordered semiconductor based systems on both sides of the Mott-Anderson metal-insulator (MI) transition. We revisit the conductivity of the i-AlCuFe and i-AlPdMn phases, which has temperature and magnetic field dependence characteristic of the metallic side of the transition. The i-AlPdRe ribbon samples can be on either side of the transition depending on their conductivity value. In all these i-phases, the density of states at the Fermi level EF is low. Its energy dependence close to EF is similar to disordered systems close to the MI transition where it is ascribed to effects of interactions between electrons and disorder.

scholarly journals Assessment of Functionals for First-Principle Studies of the Structural and Electronic Properties ofδ-Bi2O3

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
D. H. Galván ◽  
R. Núñez-González ◽  
R. Rangel ◽  
P. Alemany ◽  
A. Posada-Amarillas
Keyword(s):  
Band Structure ◽  
Charge Density ◽  
Electronic Properties ◽  
Density Of States ◽  
Lattice Parameter ◽  
Experimental Result ◽  
Ionic Character ◽  
High Symmetry ◽  
Density Profiles ◽  
Structural And Electronic Properties

Fully relativistic full-potential density functional calculations with an all-electron linearized augmented plane waves plus local orbitals method were carried out to perform a comparative study on the structural and electronic properties of the cubic oxideδ-Bi2O3phase, which is considered as one of the most promising materials in a variety of applications including fuel cells, sensors, and catalysts. Three different density functionals were used in our calculations, LDA, the GGA scheme in the parametrization of Perdew, Burke, and Ernzerhof (PBE96), and the hybrid scheme of Perdew-Wang B3PW91. The examined properties include lattice parameter, band structure and density of states, and charge density profiles. For this modification the three functionals reveal the characteristics of a metal and the existence of minigaps at high symmetry points of the band structure when spin-orbit coupling is taken into account. Density of states exhibits hybridization of Bi 6s and O 2p orbitals and the calculated charge density profiles exhibit the ionic character in the chemical bonding of this compound. The B3PW91 hybrid functional provided a better agreement with the experimental result for the lattice parameter, revealing the importance of Hartree-Fock exchange in this compound.

Novel Semiconducting Phase of Amorphous Carbon Nickel Composite Films

2006 ◽  
Vol 910 ◽  
Author(s):  
Somnath Bhattacharyya ◽  
S. J. Henley ◽  
N. P. Blanchard ◽  
S. R. P. Silva
Keyword(s):  
Laser Ablation ◽  
Fermi Level ◽  
Electronic Properties ◽  
Valence Band ◽  
Density Of States ◽  
Amorphous Carbon ◽  
Composite Films ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Diamond Like Carbon

AbstractA homogeneously mixed phase of carbon and 10% nickel yielding amorphous carbon-nickel composite (a-C-Ni) films is prepared by an excimer UV pulsed laser ablation. Conductivity study of these films shows a nearly activated conduction. Also a saturation of conductivity below a temperature of 25 K explains the presence of an additional density of states at the Fermi level in these samples. Our experiments demonstrate a very different behaviour of electronic properties of these novel materials compared to undoped diamond-like carbon (DLC) films, which was directly confirmed using valence band spectroscopy.

The Study of Electronic Density of States and Optical Properties of ZnO Nanotube by First-Principles

2015 ◽  
Vol 713-715 ◽  
pp. 2966-2969
Author(s):  
Yue Fan ◽  
Shao Chang Chen
Keyword(s):  
Optical Properties ◽  
Fermi Level ◽  
Density Of States ◽  
First Principles ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Zno Nanotube ◽  
Narrow Energy Range ◽  
Wide Energy ◽  
Better Than

In this paper, we studied the electronic density of states (DOS) and optical properties ZnO using first-principles method. We find that the electronic density of states was different in bulk ZnO and ZnO nanotube. The DOS of bulk ZnO spread at wide energy while the DOS of ZnO nanotube concentrated in a narrow energy range. The peak around-18 eV moved to a higher energy. The peaks more than Fermi level concentrated to the Fermi level, which meant the conductivity of ZnO nanotube was better than that of bulk ZnO. We also calculated the optical properties of ZnO nanotube. The optical properties showed that there were peaks around 8 eV, which may come from electrons transition between Zn 3dand O 2pstates. Our calculation provided a reference for the application of ZnO nanotube in optical devices.

Magnetic field and temperature dependences of the electrical resistance of onion structure carbon

2010 ◽  
Vol 3 (2) ◽  
pp. 95-98
Author(s):  
Evgeny N. Tkachev ◽  
Anatoliy I. Romanenko ◽  
Olga B. Anikeeva ◽  
Timofey I. Buryakov ◽  
Kamil R. Zhdanov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Physical Properties ◽  
Fermi Level ◽  
Density Of States ◽  
Electrical Resistance ◽  
Variable Range Hopping ◽  
Hopping Conductivity ◽  
Variable Range ◽  
Localization Radius ◽  
Temperature Dependences

In this paper electro physical properties of samples of onion-like carbon have been investigated. Samples have been synthesized by method of thermal graphitization of nanodiamonds. 1D Mott variable-range hopping conductivity has been observed for temperature dependences of resistance of nanoonions volume samples at temperature range 4.2 K – 300 K. Also second-degree increase of positive magnetoresistance up to 6 tesla has been revealed. Some coefficients such as localization radius a, density of states on Fermi level N(EF) have been estimated.

TEMPERATURE DEPENDENCE OF THE COMPLEX MAGNETIC SUSCEPTIBILITY FOR THE OXIDIC Y1-xZrxBa2Cu3O7-δ SUPERCONDUCTORS

2000 ◽  
Vol 14 (13) ◽  
pp. 487-493 ◽  
Author(s):  
I. G DEAC ◽  
R. REDAC ◽  
C. SBARCIOG ◽  
O. POP ◽  
I. POP
Keyword(s):  
Magnetic Susceptibility ◽  
Critical Temperature ◽  
Temperature Dependence ◽  
Inflexion Point ◽  
Thermal Variation ◽  
Critical Temperatures ◽  
Superconducting Compounds ◽  
Two Stages ◽  
Two Peaks ◽  
Weak Peak

The thermal variation of the complex magnetic susceptibility χ(T) = χ′ (T) + iχ″ (T) for the oxidic superconducting compounds Y 1-x Zr x Ba 2 Cu 3 O 7-δ, x = 0.01, 0.05 and 0.10 was investigated. The real part of the complex magnetic susceptibility χ′ (T) below critical temperature T c (χ) is negative and is lost in two stages when the temperature decreases. The inflexion point on the χ′ (T) curve corresponds to the two peaks on the temperature dependence of the imaginary part, χ″ (T), of the complex magnetic susceptibility and represents the critical temperatures for the intergranular superconductivity [Formula: see text], i = 1, 2, 3 and for the intragranular superconductivity [Formula: see text], i = 1, 2, 3. The concentration dependence of the critical temperatures is almost linear for the investigated compounds Y 1-x Zr x Ba 2 Cu 3 O 7-δ, x = 0.01, 0.05 and 0.10. The presence of the second weak peak or its absence on the χ″ (T) curves at [Formula: see text]characterizes an intense intergranular coupling.

Electronic Properties of Liquid Silicon

1985 ◽  
Vol 63 ◽  
Author(s):  
J. Q. Broughton ◽  
P. B. Allen
Keyword(s):  
Molecular Dynamics ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Optical Conductivity ◽  
Tight Binding ◽  
Liquid Silicon ◽  
Binding Parameters ◽  
Simple Cubic ◽  
Weber Potential

ABSTRACTThe electronic properties of liquid silicon were computed by coupling molecular dynamics and tight binding methods. By employing the Stillinger-Weber potential, atomic configurations of liquid Si at 1740°C were generated by molecular dynamics. Tight binding parameters chosen to fit fcc,bcc, simple cubic and diamond cubic band structures of silicon, were then used to obtain the electronic properties of the system. All states within 10eV of the Fermi level are found to be delocalized, the density of states spectrum similar (but much broadened) to that of diamond cubic silicon and the optical conductivity is found to be almost featureless with no Drude behavior.

Sign in / Sign up

Export Citation Format

Share Document