We propose a general approach based on the gradient descent method to study the inverse problem,making it possible to reversely engineer the microscopic configurations of materials that exhibit desired macroscopic pro...We propose a general approach based on the gradient descent method to study the inverse problem,making it possible to reversely engineer the microscopic configurations of materials that exhibit desired macroscopic properties.Particularly,we demonstrate its application by identifying the microscopic configurations within any given frequency range to achieve transparent phonon transport through one-dimensional harmonic lattices.Furthermore,we obtain the phonon transmission in terms of normal modes and find that the key to achieving phonon transparency or phonon blocking state lies in the ratio of the mode amplitudes at ends.展开更多
Based on the self-consistent phonon theory,the spectral energy density is calculated by the canonical transformation and the Fourier transformation.Through fitting the spectral energy density by the Lorentzian profile...Based on the self-consistent phonon theory,the spectral energy density is calculated by the canonical transformation and the Fourier transformation.Through fitting the spectral energy density by the Lorentzian profile,the phonon frequency as well as the phonon relaxation time is obtained in one-dimensional nonlinear lattices,which is validated in the Fermi-Pasta-Ulam-β(FPU-β) and φ^(4) lattices at different temperatures.The phonon mean free path is then evaluated in terms of the phonon relaxation time and phonon group velocity.The results show that,in the FPU-β lattice,the phonon mean free path as well as the phonon relaxation time displays divergent power-law behavior.The divergent exponent coincides well with that derived from the Peierls-Boltzmann theory at weak anharmonic nonlinearity.The value of the divergent exponent expects a power-law divergent heat conductivity with system size,which violates Fourier’s law.For the φ^(4) lattice,both the phonon relaxation time and mean free path are finite,which ensures normal heat conduction.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12075199)the Natural Science Foundation of Fujian Province(Grant No.2021J01006)Jiangxi Province(Grant No.20212BAB201024)。
文摘We propose a general approach based on the gradient descent method to study the inverse problem,making it possible to reversely engineer the microscopic configurations of materials that exhibit desired macroscopic properties.Particularly,we demonstrate its application by identifying the microscopic configurations within any given frequency range to achieve transparent phonon transport through one-dimensional harmonic lattices.Furthermore,we obtain the phonon transmission in terms of normal modes and find that the key to achieving phonon transparency or phonon blocking state lies in the ratio of the mode amplitudes at ends.
基金the National Natural Science Foundation of China(Grant Nos.12075199 and 11675133)。
文摘Based on the self-consistent phonon theory,the spectral energy density is calculated by the canonical transformation and the Fourier transformation.Through fitting the spectral energy density by the Lorentzian profile,the phonon frequency as well as the phonon relaxation time is obtained in one-dimensional nonlinear lattices,which is validated in the Fermi-Pasta-Ulam-β(FPU-β) and φ^(4) lattices at different temperatures.The phonon mean free path is then evaluated in terms of the phonon relaxation time and phonon group velocity.The results show that,in the FPU-β lattice,the phonon mean free path as well as the phonon relaxation time displays divergent power-law behavior.The divergent exponent coincides well with that derived from the Peierls-Boltzmann theory at weak anharmonic nonlinearity.The value of the divergent exponent expects a power-law divergent heat conductivity with system size,which violates Fourier’s law.For the φ^(4) lattice,both the phonon relaxation time and mean free path are finite,which ensures normal heat conduction.
