Hydrogen Isotopic Effects of Uranium Hydrides: First-Principles Calculations

2015 ◽  
Vol 817 ◽  
pp. 675-684 ◽  
Author(s):  
Hai Yan Lu
Keyword(s):  
Raman Spectrum ◽  
First Principles ◽  
Density Functional ◽  
Coulomb Repulsion ◽  
Local Spin Density Approximation ◽  
Functional Theory ◽  
Lattice Constants ◽  
Isotopic Effects ◽  
Typical Frequency ◽  
Good Agreement

In this paper, we study the ground-state and lattice dynamical properties of β-UH--3by means of the first-principles density functional theory within the local spin-density approximation (LSDA)+Uformulism. The lattice constants and electronic structure are correctly described by taking into account the strong on-site Coulomb repulsion among the 5felectrons localized on uranium atoms. Good agreement with experiments is achieved by tuning the effective Hubbard parameter at around 4 eV. The phonon band structure confirms the dynamical stability of β-UH--3, and the Raman-active modes are consistent with Raman spectrum measurements. The substitution of the deuterium (tritium) atom for hydrogen atom makes significant variations in the typical frequency of Raman-active modes. It is found that the Raman-active mode frequency is approximately inversely proportional to the square root of the hydrogen isotope mass. We conclude that Raman spectrum provides a powerful method for detecting hydrogen isotopic effects.

scholarly journals Effect of Doping on the Thermoelectric Properties of Thallium Tellurides Using First Principles Calculations

2011 ◽  
Vol 172-174 ◽  
pp. 985-989 ◽  
Author(s):  
Philippe Jund ◽  
Xiao Ma Tao ◽  
Romain Viennois ◽  
Jean Claude Tédenac
Keyword(s):  
Experimental Data ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Pure Compound ◽  
Functional Theory ◽  
Lattice Constants ◽  
Thallium Tellurides ◽  
Good Agreement

We present a study of the electronic properties of Tl5Te3, BiTl9Te6and SbTl9Te6compounds by means of density functional theory based calculations. The optimized lattice constants of the compounds are in good agreement with the experimental data. The band gap of BiTl9Te6and SbTl9Te6compounds are found to be equal to 0.589 eV and 0.538 eV, respectively and are in agreement with the available experimental data. To compare the thermoelectric properties of the different compounds we calculate their thermopower using Mott’s law and show, as expected experimentally, that the substituted tellurides have much better thermoelectric properties compared to the pure compound.

scholarly journals Many-Body Effects in FeN4 Center Embedded in Graphene

2020 ◽  
Vol 10 (7) ◽  
pp. 2542 ◽  
Author(s):  
Andrew Allerdt ◽  
Hasnain Hafiz ◽  
Bernardo Barbiellini ◽  
Arun Bansil ◽  
Adrian E. Feiguin
Keyword(s):  
Transition Metal Complexes ◽  
First Principles ◽  
Density Functional ◽  
Coulomb Repulsion ◽  
Density Matrix Renormalization Group ◽  
Orbital Interaction ◽  
Many Body ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Density Matrix Renormalization

We introduce a computational approach to study porphyrin-like transition metal complexes, bridging density functional theory and exact many-body techniques, such as the density matrix renormalization group (DMRG). We first derive a multi-orbital Anderson impurity Hamiltonian starting from first principles considerations that qualitatively reproduce generalized gradient approximation (GGA)+U results when ignoring inter-orbital Coulomb repulsion U ′ and Hund exchange J. An exact canonical transformation is used to reduce the dimensionality of the problem and make it amenable to DMRG calculations, including all many-body terms (both intra- and inter-orbital), which are treated in a numerically exact way. We apply this technique to FeN 4 centers in graphene and show that the inclusion of these terms has dramatic effects: as the iron orbitals become single occupied due to the Coulomb repulsion, the inter-orbital interaction further reduces the occupation, yielding a non-monotonic behavior of the magnetic moment as a function of the interactions, with maximum polarization only in a small window at intermediate values of the parameters. Furthermore, U ′ changes the relative position of the peaks in the density of states, particularly on the iron d z 2 orbital, which is expected to affect the binding of ligands greatly.

Electronic and optical properties of K-doped ZnO: Ab initio study

2016 ◽  
Vol 30 (23) ◽  
pp. 1650291 ◽  
Author(s):  
D. E. Aimouch ◽  
S. Meskine ◽  
R. Hayn ◽  
A. Zaoui ◽  
A. Boukortt
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Complete Analysis ◽  
Local Spin Density Approximation ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Text Type ◽  
Doped Zno ◽  
Optical Applications ◽  
Good Agreement

We present the results of ab initio calculations of K-doped ZnO in the wurtzite structure using a supercell of 32 atoms and density functional theory. A complete analysis of its electronic, optical and magnetic properties is provided. The local spin density approximation (LSDA) has been used to analyze the density of states and to understand the K influence at different concentration values. The material is revealed to become a [Formula: see text]-type doped semiconductor. The optical constant or refractive index, the dielectric function, and the absorption coefficient were determined and show a good agreement with available experimental data. Potassium doping leads to an absorption peak at about 380 nm. That peak might improve the absorption characteristics of ZnO for solar cell or optical applications.

Newly Determined Crystal Structure and Optical Property of the Intermetallic NiAl and Ni3Al Alloys: A First-Principles Computer Simulated Investigation

2014 ◽  
Vol 989-994 ◽  
pp. 220-223
Author(s):  
Chao Xu ◽  
Dong Chen
Keyword(s):  
Dielectric Function ◽  
Loss Function ◽  
First Principles ◽  
Density Functional ◽  
Peak Height ◽  
Functional Theory ◽  
Lattice Constants ◽  
Light Region ◽  
The Density Functional Theory ◽  
Lower Energy Region

Using quantum mechanics plane-wave approach based on the density functional theory, the lattice constants of NixAl at different Ni concentrations (x=1, 3) are predicted. Optical properties such as dielectric function, energy loss function and reflectivity are also investigated. Results show that with the increase of Ni constituent, the location of the peak in loss function moves to the lower energy region, but the peak height increases. At 0eV, the reflectivity increases rapidly with the Ni concentration. The reflectivity of NiAl and Ni3Al are pronounced in the UV region (not in the visible light region). The dielectric properties, namely the real and imaginary parts of the dielectric function, changed significantly with Ni constituent.

scholarly journals First-principles study on electronic, optic, elastic, dynamic and thermodynamic properties of RbH compound

2015 ◽  
Vol 6 ◽  
pp. A6 ◽  
Author(s):  
Sinem Erden Gulebaglan ◽  
Emel Kilit Dogan ◽  
Mehmet Nurullah Secuk ◽  
Murat Aycibin ◽  
Bahattin Erdinc ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Band Gap ◽  
Lattice Constant ◽  
First Principles ◽  
Density Functional ◽  
Temperature Dependent ◽  
Functional Theory ◽  
Salt Structure ◽  
Elastic Lattice ◽  
Good Agreement

We performed first-principles calculations to obtain the electronic, optical, elastic, lattice-dynamical and thermodynamic properties of RbH compound with rock salt structure. The ground-state properties, i.e., the lattice constant and the band gap were investigated using a plane wave pseudopotential method within density functional theory. The calculated lattice constant, bulk modulus, energy band gap and elastic constants are reported and compared with previous theoretical and experimental results. Our calculated results and the previous results which are obtained from literature are in a good agreement. Moreover, real and imaginary parts of complex dielectric function, reflectivity spectrum, absorption, extinction coefficient and loss function as a function of photon energy and refractive index with respect to photon wavelength were calculated. In addition, temperature dependent thermodynamic properties such as Helmholtz free energy, internal energy, entropy and specific heat have been studied.

Atomistic Simulation and Density Functional Analysis of Ni(111)-ZrO2(100)(Cubic) and NiO(111)-Ni(111)-ZrO2(100)(Cubic) Interfaces

2000 ◽  
Vol 654 ◽  
Author(s):  
Chang-Xin Guo ◽  
Donald E. Ellis ◽  
Vinayak P. Dravid ◽  
Luke Brewer
Keyword(s):  
First Principles ◽  
Atomistic Simulation ◽  
Density Functional ◽  
Depth Profiling ◽  
Interface Plane ◽  
Functional Theory ◽  
Spatially Resolved ◽  
Microscopy Data ◽  
Energy Profiling ◽  
Good Agreement

AbstractThe atomic arrangement and electronic structure in the vicinity of Ni(111)- ZrO2(100)(Cubic) and NiO(111)-Ni(111)-ZrO2(100)(Cubic) interfaces have been studied by atomistic simulation and by first-principles Density Functional theory. “Depth Profiling” is carred out in both methodologies, to determine modifications of cohesive energy and electron distribution of atomic layers from the interface plane. The energy profiling results show the interface consists of only a few atomic layers. Simulation results and electron density analyses are in good agreement with High Resolution Spatially Resolved Electron Microscopy data.

Composition and Strain Dependence of the Piezoelectric Coefficients in Semiconductor Alloys

2007 ◽  
Vol 1017 ◽  
Author(s):  
T. Hammerschmidt ◽  
M. A. Migliorato ◽  
D. Powell ◽  
A. G. Cullis ◽  
G. P. Srivastava
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Piezoelectric Coefficient ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Semiconductor Alloys ◽  
Binding Model ◽  
Functional Theory ◽  
Photo Current ◽  
Good Agreement

AbstractWe propose a tight-binding model for the polarization that considers direct and dipole contributions and employs microscopic quantities that can be calculated by first-principles methods, e.g. by employing Density Functional Theory (DFT). Applying our model to InxGa1-xAs alloys allows us to settle discrepancies between the values of e14 as obtained from experiments and from linear interpolations between the values of InAs and GaAs. Our calculated piezoelectric coefficient is in very good agreement with photo current measurements of InAs/GaAs(111) quantum well samples.

Theoretical Characterization of Thermodynamic, Magnetic and Electronic Proprieties of Full-Heusler Co2YGa (Y = V, Cr and Mn) Alloys

SPIN ◽  
2020 ◽  
Vol 10 (01) ◽  
pp. 2050005
Author(s):  
M. Mokhtari ◽  
D. Amari ◽  
F. Dahmane ◽  
G. Benabdellah ◽  
L. Zekri ◽  
...  
Keyword(s):  
Density Functional ◽  
Heusler Alloys ◽  
Debye Model ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Half Metallic ◽  
Lattice Constants ◽  
Full Heusler ◽  
Good Agreement

The electronic structure, magnetism and thermal proprieties of the full-Heusler alloys Co2YGa (Y [Formula: see text] V, Cr and Mn) have been investigated by first-principles calculations based on density functional theory with the generalized gradient approximation (GGA). Our obtained results of lattice parameters show reasonable agreement to the previously reported experimental and other theoretical studies. The calculations show that all Co2YGa (Y [Formula: see text] V, Cr and Mn) alloys belong to half-metallic compound with a magnetic moment of 2.00, 3.00 and 4.00 [Formula: see text] at their respective equilibrium lattice constants which is in good agreement with the Slater–Pauling rule and perfect 100% spin polarization at the Fermi level. The thermal effect on the macroscopic properties of these alloys is presented such as the thermal expansion coefficient, heat capacity and Debye temperature, based on the quasi-harmonic Debye model.

scholarly journals Structural, Elastic, Electronic and Optical Properties of SrTMO3 (TM = Rh, Zr) Compounds: Insights from FP-LAPW Study

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2057 ◽  
Author(s):  
Areej Shawahni ◽  
Mohammed Abu-Jafar ◽  
Raed Jaradat ◽  
Tarik Ouahrani ◽  
Rabah Khenata ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Ultraviolet Region ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Lattice Constants ◽  
Far Ultraviolet ◽  
Theoretical Results ◽  
Good Agreement

The structural, mechanical, electronic and optical properties of SrTMO3 (TM = Rh, Zr) compounds are investigated by using first principle calculations based on density functional theory (DFT). The exchange-correlation potential was treated with the generalized gradient approximation (GGA) for the structural properties. Moreover, the modified Becke-Johnson (mBJ) approximation was also employed for the electronic properties. The calculated lattice constants are in good agreement with the available experimental and theoretical results. The elastic constants and their derived moduli reveal that SrRhO3 is ductile and SrZrO3 is brittle in nature. The band structure and the density of states calculations with mBJ-GGA predict a metallic nature for SrRhO3 and an insulating behavior for SrZrO3. The optical properties reveal that both SrRhO3 and SrZrO3 are suitable as wave reflectance compounds in the whole spectrum for SrRhO3 and in the far ultraviolet region (FUV) for SrZrO3.

First-principles investigation of the elastic and thermodynamic properties of ReC2 (Re = Ho, Nd, Pr)

2015 ◽  
Vol 29 (01) ◽  
pp. 1450256 ◽  
Author(s):  
Wen Huang ◽  
Haichuan Chen
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Lattice Constants ◽  
Generalized Gradient Approximation ◽  
Temperature Melting

The elastic and thermodynamic properties of Re C 2 (Re = Ho , Nd , Pr ) have been investigated by using the first-principles density functional theory within the generalized gradient approximation. The computed lattice constants of Re C 2 are in agreement with the experimental data. The calculated elastic constants reveal that all compounds are mechanically stable. The shear modulus, Young's modulus, Poisson's ratio σ, the ratio B/G, shear anisotropy and elastic anisotropy are also calculated. Finally, the Vicker hardness, Debye temperature, melting point and thermal conductivity have been predicted.

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