The Experts below are selected from a list of 37524 Experts worldwide ranked by ideXlab platform
Atsushi Togo - One of the best experts on this subject based on the ideXlab platform.
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Phonon Structure of titanium under shear deformation along 10 1 2 twinning mode
Physical Review B, 2020Co-Authors: Atsushi Togo, Yuta Inoue, Isao TanakaAbstract:We investigated Phonon behavior of hexagonal close-packed titanium under homogeneous shear deformation corresponding to the ${10\overline{1}2}$ twinning mode using first-principles calculations and Phonon calculations. By this deformation, we found that a Phonon mode located at a point on the Brillouin zone boundary is drastically softened, increasing the shear, and finally it triggers a spontaneous structural transition by breaking the crystal symmetry toward twin from parent.
Joseph P Feser - One of the best experts on this subject based on the ideXlab platform.
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a framework for solving atomistic Phonon Structure scattering problems in the frequency domain using perfectly matched layer boundaries
Journal of Applied Physics, 2015Co-Authors: Rohit R Kakodkar, Joseph P FeserAbstract:We present a numerical approach to the solution of elastic Phonon-interface and Phonon-nanoStructure scattering problems based on a frequency-domain decomposition of the atomistic equations of motion and the use of perfectly matched layer (PML) boundaries. Unlike molecular dynamic wavepacket analysis, the current approach provides the ability to simulate scattering from individual Phonon modes, including wavevectors in highly dispersive regimes. Like the atomistic Green's function method, the technique reduces scattering problems to a system of linear algebraic equations via a sparse, tightly banded matrix regardless of dimensionality. However, the use of PML boundaries enables rapid absorption of scattered wave energies at the boundaries and provides a simple and inexpensive interpretation of the scattered Phonon energy flux calculated from the energy dissipation rate in the PML. The accuracy of the method is demonstrated on connected monoatomic chains, for which an analytic solution is known. The parameters defining the PML are found to affect the performance and guidelines for selecting optimal parameters are given. The method is used to study the energy transmission coefficient for connected diatomic chains over all available wavevectors for both optical and longitudinal Phonons; it is found that when there is discontinuity between sublattices, even connected chains of equivalent acoustic impedance have near-zero transmission coefficient for short wavelengths. The Phonon scattering cross section of an embedded nanocylinder is calculated in 2D for a wide range of frequencies to demonstrate the extension of the method to high dimensions. The calculations match continuum theory for long-wavelength Phonons and large cylinder radii, but otherwise show complex physics associated with discreteness of the lattice. Examples include Mie oscillations which terminate when incident Phonon frequencies exceed the maximum available frequency in the embedded nanocylinder, and scattering efficiencies larger than two near the Brillouin zone edge.
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a framework for solving atomistic Phonon Structure scattering problems in the frequency domain using perfectly matched layer boundaries
arXiv: Mesoscale and Nanoscale Physics, 2015Co-Authors: Rohit R Kakodkar, Joseph P FeserAbstract:We present a numerical approach to the solution of elastic Phonon scattering problems based on a frequency domain decomposition of the atomistic equations of motion and the use of perfectly matched layer or PML boundaries. Unlike MD wavepacket analysis, the current approach has the ability to simulate scattering from individual Phonon modes, including wavevectors in highly dispersive regimes. Like the Atomistic Green's Function method, the technique reduces scattering problems to a system of linear algebraic equations via a sparse, banded matrix. However, the use of PML boundaries enables rapid absorption of scattered wave energies at the boundaries, and provides a simple and inexpensive interpretation of the scattered Phonon energy flux calculated from the energy dissipation rate in the PML. The accuracy of the method is demonstrated on connected monoatomic chains, for which an analytic solution is known. The parameters defining the PML are found to affect the performance and guidelines for selecting optimal parameters are given. The method is used to study the energy transmission coefficient for connected diatomic chains over all available wavevectors for both optical and longitudinal Phonons; it is found that when there is discontinuity between sublattices, even connected chains of equivalent acoustic impedence have near-zero transmission coefficient for short wavelengths. The Phonon scattering cross section of an embedded nanocylinder is calculated for a wide range of frequencies to demonstrate the extension of the method to high dimensions. The calculations match continuum theory for long wavelength Phonons and large cylinder radii, but otherwise show complex physics including Mie oscillations which terminate when incident Phonon frequencies exceeds the maximum available frequency in the embedded nanocylinder, and scattering efficiencies larger than two near the Brillouin zone edge.
Isao Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Phonon Structure of titanium under shear deformation along 10 1 2 twinning mode
Physical Review B, 2020Co-Authors: Atsushi Togo, Yuta Inoue, Isao TanakaAbstract:We investigated Phonon behavior of hexagonal close-packed titanium under homogeneous shear deformation corresponding to the ${10\overline{1}2}$ twinning mode using first-principles calculations and Phonon calculations. By this deformation, we found that a Phonon mode located at a point on the Brillouin zone boundary is drastically softened, increasing the shear, and finally it triggers a spontaneous structural transition by breaking the crystal symmetry toward twin from parent.
Rohit R Kakodkar - One of the best experts on this subject based on the ideXlab platform.
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a framework for solving atomistic Phonon Structure scattering problems in the frequency domain using perfectly matched layer boundaries
Journal of Applied Physics, 2015Co-Authors: Rohit R Kakodkar, Joseph P FeserAbstract:We present a numerical approach to the solution of elastic Phonon-interface and Phonon-nanoStructure scattering problems based on a frequency-domain decomposition of the atomistic equations of motion and the use of perfectly matched layer (PML) boundaries. Unlike molecular dynamic wavepacket analysis, the current approach provides the ability to simulate scattering from individual Phonon modes, including wavevectors in highly dispersive regimes. Like the atomistic Green's function method, the technique reduces scattering problems to a system of linear algebraic equations via a sparse, tightly banded matrix regardless of dimensionality. However, the use of PML boundaries enables rapid absorption of scattered wave energies at the boundaries and provides a simple and inexpensive interpretation of the scattered Phonon energy flux calculated from the energy dissipation rate in the PML. The accuracy of the method is demonstrated on connected monoatomic chains, for which an analytic solution is known. The parameters defining the PML are found to affect the performance and guidelines for selecting optimal parameters are given. The method is used to study the energy transmission coefficient for connected diatomic chains over all available wavevectors for both optical and longitudinal Phonons; it is found that when there is discontinuity between sublattices, even connected chains of equivalent acoustic impedance have near-zero transmission coefficient for short wavelengths. The Phonon scattering cross section of an embedded nanocylinder is calculated in 2D for a wide range of frequencies to demonstrate the extension of the method to high dimensions. The calculations match continuum theory for long-wavelength Phonons and large cylinder radii, but otherwise show complex physics associated with discreteness of the lattice. Examples include Mie oscillations which terminate when incident Phonon frequencies exceed the maximum available frequency in the embedded nanocylinder, and scattering efficiencies larger than two near the Brillouin zone edge.
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a framework for solving atomistic Phonon Structure scattering problems in the frequency domain using perfectly matched layer boundaries
arXiv: Mesoscale and Nanoscale Physics, 2015Co-Authors: Rohit R Kakodkar, Joseph P FeserAbstract:We present a numerical approach to the solution of elastic Phonon scattering problems based on a frequency domain decomposition of the atomistic equations of motion and the use of perfectly matched layer or PML boundaries. Unlike MD wavepacket analysis, the current approach has the ability to simulate scattering from individual Phonon modes, including wavevectors in highly dispersive regimes. Like the Atomistic Green's Function method, the technique reduces scattering problems to a system of linear algebraic equations via a sparse, banded matrix. However, the use of PML boundaries enables rapid absorption of scattered wave energies at the boundaries, and provides a simple and inexpensive interpretation of the scattered Phonon energy flux calculated from the energy dissipation rate in the PML. The accuracy of the method is demonstrated on connected monoatomic chains, for which an analytic solution is known. The parameters defining the PML are found to affect the performance and guidelines for selecting optimal parameters are given. The method is used to study the energy transmission coefficient for connected diatomic chains over all available wavevectors for both optical and longitudinal Phonons; it is found that when there is discontinuity between sublattices, even connected chains of equivalent acoustic impedence have near-zero transmission coefficient for short wavelengths. The Phonon scattering cross section of an embedded nanocylinder is calculated for a wide range of frequencies to demonstrate the extension of the method to high dimensions. The calculations match continuum theory for long wavelength Phonons and large cylinder radii, but otherwise show complex physics including Mie oscillations which terminate when incident Phonon frequencies exceeds the maximum available frequency in the embedded nanocylinder, and scattering efficiencies larger than two near the Brillouin zone edge.
Yuta Inoue - One of the best experts on this subject based on the ideXlab platform.
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Phonon Structure of titanium under shear deformation along 10 1 2 twinning mode
Physical Review B, 2020Co-Authors: Atsushi Togo, Yuta Inoue, Isao TanakaAbstract:We investigated Phonon behavior of hexagonal close-packed titanium under homogeneous shear deformation corresponding to the ${10\overline{1}2}$ twinning mode using first-principles calculations and Phonon calculations. By this deformation, we found that a Phonon mode located at a point on the Brillouin zone boundary is drastically softened, increasing the shear, and finally it triggers a spontaneous structural transition by breaking the crystal symmetry toward twin from parent.