Thermoelectric and piezoelectric properties of the predicted AlxIn1−xN composites based on ab initio calculations

2017 ◽  
Vol 19 (36) ◽  
pp. 24613-24625 ◽  
Author(s):  
Yee Hui Robin Chang ◽  
Tiem Leong Yoon ◽  
Thong Leng Lim ◽  
Moi Hua Tuh ◽  
Eong Sheng Goh
Keyword(s):  
Perturbation Theory ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Piezoelectric Properties ◽  
Boltzmann Transport ◽  
Density Functional Perturbation Theory ◽  
Theoretical Investigations ◽  
Piezoelectric Characteristics

Theoretical investigations of the thermoelectric and piezoelectric characteristics in the AlxIn1−xN system have been carried out based on a first principles approach in combination with the semi-classical Boltzmann transport concept and density functional perturbation theory.

Assignment of Raman-active vibrational modes of tetragonal mackinawite: Raman investigations and ab initio calculations

RSC Advances ◽  
2014 ◽  
Vol 4 (49) ◽  
pp. 25827-25834 ◽  
Author(s):  
Y. El Mendili ◽  
B. Minisini ◽  
A. Abdelouas ◽  
J.-F. Bardeau
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Direct Methods ◽  
Vibrational Modes ◽  
Dispersion Correction ◽  
Density Functional Perturbation Theory ◽  
Calculation Results

We report on the first assignment of the Raman-active vibrational modes of mackinawite using Density Functional Perturbation Theory and direct methods with BLYP + dispersion correction. Based on experimental data and calculation results, the Raman bands were assigned as 236 cm−1 (B1g), 256 cm−1 (Eg), 376 cm−1 (A1g) and 395 cm−1 (Eg).

Hydrogenation as a source of superconductivity in two-dimensional TiB2

2021 ◽  
pp. 2150057
Author(s):  
Hui Wang ◽  
Chen Pan ◽  
Sheng-Yan Wang ◽  
Hong Jiang ◽  
Yin-Chang Zhao ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Vibration Frequency ◽  
First Principles ◽  
Density Functional ◽  
Tensile Strain ◽  
2D Materials ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Density Functional Perturbation Theory ◽  
Potential Applications

Using first-principles calculations based on density functional perturbation theory, we demonstrate hydrogenation-induced superconductivity in monolayer TiB2H. Hydrogen adatoms destroy the Dirac state of monolayer TiB2 and monolayer TiB2H has a high vibration frequency. Monolayer TiB2H is a phonon-mediated superconductor. Monolayer TiB2H has a predicted [Formula: see text] of 8[Formula: see text]K, which further increases under external tensile strain. Thus, this study extends our understanding of superconductivity in two-dimensional (2D) materials and its potential applications.

First-Principles Study of Structural and Vibrational Properties of α-SiO2 under Pressure

2015 ◽  
Vol 775 ◽  
pp. 191-196
Author(s):  
Xiao Wei Lei ◽  
Yong Song ◽  
Kuo Yang ◽  
Hui Zhao
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Infrared Spectra ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Vibrational Properties ◽  
Vibrational Modes ◽  
Density Functional Perturbation Theory ◽  
Good Agreement

Using first principles approach, we present the structural, vibrational and dielectric properties of α-SiO2. The calculations have been carried out within the density functional perturbation theory and linear response formalism using the norm-concerving pseudopotentials and a plane wave basis. All the vibrational modes identified are in good agreement with experiment. The calculated infrared spectra are also in good agreement with available experimental results both for the positions and the intensities of the main peaks. We find that the modes Eu7 and A2u4 splits in two respectively at high hydrostaticpressures. Then we calculate the infrared spectra under high pressure of different orientations. The vibrational modes in different phase transitions are reported and discussed respectively.

scholarly journals Ab initio and first principles theoretical investigations of triplet–triplet fluorescence in trimethylenemethane biradicals

RSC Advances ◽  
2016 ◽  
Vol 6 (87) ◽  
pp. 83668-83672 ◽  
Author(s):  
Yasunori Matsui ◽  
Kosuke Usui ◽  
Hiroshi Ikeda ◽  
Stephan Irle
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Hartree Fock ◽  
Theoretical Investigations

Theoretical studies on triplet–triplet (T1 → T0) fluorescence of the arylated trimethylenemethane (TMM) biradicals, 32˙˙, were carried out using post-Hartree–Fock ab initio and various first principles density functional theory methods.

First-principle studies of the lattice dynamics of crystals, and related properties

2005 ◽  
Vol 220 (5/6) ◽  
Author(s):  
Xavier Gonze ◽  
Gian-Marco Rignanese ◽  
Razvan Caracas
Keyword(s):  
Perturbation Theory ◽  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Computational Method ◽  
Dielectric Tensor ◽  
Atomic Temperature ◽  
Density Functional Perturbation Theory ◽  
Infra Red ◽  
Temperature Factors

AbstractThe crystal lattice is never rigid. Due to temperature, external fields or pressure, the nuclei vibrate, the lattice distorts, and instabilities can induce phase transitions. We review the basic concepts of density-functional perturbation theory, a computational method especially suited to determine from first-principles the microscopic parameters governing such behaviour. Then, we present the additional formalism leading to the following properties of minerals: the infra-red and Raman spectra; the prediction of (meta)stability or instability of a crystalline phase, based on the phonon spectrum; the computation of thermodynamics quantities like the free energy, entropy, specific heat; the atomic temperature factors. For each property, examples are given. When appropriate, we mention the computation of related properties, like dielectric tensor and Born effective charges that are needed to get infra-red spectra. Finally, we discuss briefly, on one hand, other applications of the density-functional perturbation theory, and, on the other hand, an alternative technique, the finite-difference computation of dynamical matrices.

Phonon Thermal Transport in Bulk and Nanostructured Materials From First Principles

2008 ◽  
Author(s):  
D. A. Broido ◽  
Natalio Mingo ◽  
Derek Stewart
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Nanostructured Materials ◽  
Thermal Transport ◽  
Density Functional ◽  
Thermal Conductance ◽  
Density Functional Perturbation Theory ◽  
Molecular Dynamics Calculations ◽  
Substitutional Defects ◽  
Silicon And Germanium

Current theories of phonon thermal transport in nanomaterials are often based on highly parametrized approximations or on purely classical molecular dynamics calculations. We present a rigorous theoretical approach to accurately describe phonon thermal transport in bulk and nanostructured materials. This technique is based on Boltzmann and non-equilibrium Green’s function calculations of thermal transport, and employs ab-initio calculations of harmonic and anharmonic interatomic force constants using density functional perturbation theory. The approach has been applied to bulk semiconductors, where excellent agreement is obtained between the calculated and measured intrinsic lattice thermal conductivities of silicon and germanium without any adjustable parameters. In addition, ab initio calculations of phonon thermal conductance in carbon nanotubes with isolated Stone-Wales and substitutional defects are presented and discussed.

scholarly journals Thermodynamic properties of pure and doped (B, N) graphene

RSC Advances ◽  
2016 ◽  
Vol 6 (15) ◽  
pp. 12158-12168 ◽  
Author(s):  
Sarita Mann ◽  
Pooja Rani ◽  
Ranjan Kumar ◽  
Girija S. Dubey ◽  
V. K. Jindal
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Graphene Sheet ◽  
Density Functional ◽  
Thermodynamical Properties ◽  
Density Functional Perturbation Theory ◽  
Doped Graphene

Ab initio density functional perturbation theory (DFPT) has been employed to study the thermodynamical properties of pure and doped graphene sheet and the results have been compared with available theoretical and experimental data.

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