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.

scholarly journals Theoretical Studies of the Stone-Wales Defect in C36 Fullerene Embedded inside Zigzag Carbon Nanotube

2016 ◽  
Vol 2016 ◽  
pp. 1-4 ◽  
Author(s):  
Konstantin S. Grishakov ◽  
Konstantin P. Katin ◽  
Mikhail M. Maslov
Keyword(s):  
Density Functional Theory ◽  
Carbon Nanotube ◽  
Density Functional ◽  
Activation Barrier ◽  
Tight Binding ◽  
Theoretical Studies ◽  
Tight Binding Model ◽  
Binding Model ◽  
Functional Theory ◽  
Wales Defect

We apply density functional theory at PBE/6-311G(d) level as well as nonorthogonal tight-binding model to study the Stone-Wales transformation in C36 fullerene embedded inside the (14,0) zigzag carbon nanotube. We optimize geometries of two different isomers with the D2d and the D6h symmetries and the transition state dividing them. The mechanism of Stone-Wales transformation from D2d to D6h symmetry for the encapsulated C36 is calculated to be the same as for the isolated one. It is found that the outer carbon wall significantly stabilizes the D6h isomer. However, carbon nanotube reduces the activation barrier of Stone-Wales rearrangement by 0.4 eV compared with the corresponding value for the isolated C36.

scholarly journals Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4248
Author(s):  
Fengmiao Li ◽  
Yuting Zou ◽  
Myung-Geun Han ◽  
Kateryna Foyevtsova ◽  
Hyungki Shin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Tight Binding ◽  
Crystal Form ◽  
Titanium Monoxide ◽  
Binding Model ◽  
Functional Theory ◽  
Single Crystalline ◽  
First Time ◽  
Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

Investigating 3,4-bis(3-nitrofurazan-4-yl)furoxan detonation with a rapidly tuned density functional tight binding model

2021 ◽  
Vol 154 (16) ◽  
pp. 164115
Author(s):  
Rebecca K. Lindsey ◽  
Sorin Bastea ◽  
Nir Goldman ◽  
Laurence E. Fried
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Binding Model

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 A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions

2014 ◽  
Vol 118 (29) ◽  
pp. 5520-5528 ◽  
Author(s):  
Sriram Goverapet Srinivasan ◽  
Nir Goldman ◽  
Isaac Tamblyn ◽  
Sebastien Hamel ◽  
Michael Gaus
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Basis Set ◽  
Tight Binding Model ◽  
Binding Model ◽  
Thermodynamic Conditions ◽  
Three Body ◽  
Extended Basis

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.

Electronic Structure of Fullerene Tubules

1992 ◽  
Vol 247 ◽  
Author(s):  
J. W. Mintmire ◽  
D. H. Robertson ◽  
B. I. Dunlap ◽  
R. C. Mowrey ◽  
D. W. Brenner ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Tight Binding ◽  
Small Diameter ◽  
High Symmetry ◽  
Binding Model ◽  
High Carrier ◽  
Reasonable Description ◽  
Gaussian Orbital

ABSTRACTRecent reports suggest that graphitic tubules with diameters on the order of fullerene diameters have been synthesized. Such small-diameter tubules should have electronic properties related to those of two-dimensional graphite. We demonstrate by comparison with results from a first-principles, self-consistent, all-electron Gaussian-orbital based local-density functional approach that an all-valence tight-binding model can be expected to give a reasonable description of the electronic states of these tubules. In analyzing both high-symmetry tubules and lower-symmetry chiral tubules, we see that a relatively high carrier density could be expected for many of these structures.

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