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.

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).

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.

scholarly journals Phonons in Short-Period GaN/AlN Superlattices: Group-Theoretical Analysis, Ab initio Calculations, and Raman Spectra

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 286
Author(s):  
Valery Davydov ◽  
Evgenii Roginskii ◽  
Yuri Kitaev ◽  
Alexander Smirnov ◽  
Ilya Eliseyev ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Density Functional ◽  
Structural Characteristics ◽  
Vibrational Modes ◽  
Phonon Modes ◽  
Short Period ◽  
Group Theoretical Analysis

We report the results of experimental and theoretical studies of phonon modes in GaN/AlN superlattices (SLs) with a period of several atomic layers, grown by submonolayer digital plasma-assisted molecular-beam epitaxy, which have a great potential for use in quantum and stress engineering. Using detailed group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals is established. Ab initio calculations in the framework of the density functional theory, aimed at studying the phonon states, are performed for SLs with both equal and unequal layer thicknesses. The frequencies of the vibrational modes are calculated, and atomic displacement patterns are obtained. Raman spectra are calculated and compared with the experimental ones. The results of the ab initio calculations are in good agreement with the experimental Raman spectra and the results of the group-theoretical analysis. As a result of comprehensive studies, the correlations between the parameters of acoustic and optical phonons and the structure of SLs are obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy. The results obtained can be used to optimize the growth technologies aimed to form structurally perfect short-period GaN/AlN SLs.

scholarly journals Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5481
Author(s):  
Marcin Sikora ◽  
Anna Bajorek ◽  
Artur Chrobak ◽  
Józef Deniszczyk ◽  
Grzegorz Ziółkowski ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Magnetic Measurements ◽  
Plane Waves ◽  
Full Potential ◽  
Theory Approach ◽  
Xps Spectra

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.

scholarly journals Polydopamine and eumelanin molecular structures investigated with ab initio calculations

2017 ◽  
Vol 8 (2) ◽  
pp. 1631-1641 ◽  
Author(s):  
Chun-Teh Chen ◽  
Francisco J. Martin-Martinez ◽  
Gang Seob Jung ◽  
Markus J. Buehler
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Molecular Structures ◽  
Brute Force ◽  
Functional Theory

A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin.

Ab initio study of structural, electronic, and thermal properties of Pt1−xPdx alloys

2017 ◽  
Vol 31 (01) ◽  
pp. 1650243 ◽  
Author(s):  
Shabbir Ahmed ◽  
Muhammad Zafar ◽  
M. Shakil ◽  
M. A. Choudhary ◽  
Muhammad Raza-Ur-Rehman Hashmi
Keyword(s):  
Thermal Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Harmonic Approximation ◽  
Linear Response Theory ◽  
Potential Method ◽  
Lattice Constants ◽  
Debye Temperatures ◽  
Density Functional Perturbation Theory ◽  
Densities Of States

We report a systematic theoretical study of Pt[Formula: see text]Pd[Formula: see text] alloys using ab initio density functional theory (DFT) by pseudo potential method. We have used super cell approach to investigate structural, electronic and thermal properties of Platinum (Pt), Palladium (Pd) and their alloys Pt[Formula: see text]Pd[Formula: see text]([Formula: see text] = 0.00, 0.25, 0.50, 0.75, 1.00). The calculated lattice constants and bulk moduli are in good agreement with available literature data. The results of electronic properties revealed that the alloys are metallic in nature. The thermal properties were investigated through density functional perturbation theory (DFPT) and quasi-harmonic approximation. The contribution to the free energy from the lattice vibration was calculated using the phonon densities of states (DOS) derived by means of the linear-response theory. The DFPT with quasi-harmonic approximation methods was applied to determine the phonon DOS and thermal quantities i.e., the Debye temperatures, vibration energy, entropy and constant-volume specific heat.

scholarly journals Armchair Boron Nitride nanotubes—heterocyclic molecules interactions: A computational description

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Ernesto Chigo Anota ◽  
Gregorio Hernández Cocoletzi ◽  
Andres Manuel Garay Tapia
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Boron Nitride Nanotubes ◽  
Functional Theory ◽  
Heterocyclic Molecules ◽  
Non Covalent Interactions ◽  
Covalent Interactions

AbstractAb-initio calculations using density functional theory (DFT) are used to investigate the non-covalent interactions between single wall armchair boron nitride nanotubes (BNNTs) with open ends and several heterocyclic molecules: thiophene (T; C

Ab initio calculations of quantum transport of Au–GaN–Au nanoscale junctions

RSC Advances ◽  
2014 ◽  
Vol 4 (94) ◽  
pp. 51838-51844 ◽  
Author(s):  
Tian Zhang ◽  
Yan Cheng ◽  
Xiang-Rong Chen
Keyword(s):  
Density Functional Theory ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Transport Properties ◽  
Quantum Transport ◽  
Electronic Transport ◽  
Density Functional ◽  
Function Method ◽  
Functional Theory ◽  
Non Equilibrium Green’S Function

We investigate the contact geometry and electronic transport properties of a GaN pair sandwiched between Au electrodes by performing density functional theory plus the non-equilibrium Green's function method.

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