We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with t...We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with temperature decreases by increasing density. For density ρ＊ = ρσ3 = 0.84 we observe a peak at the value of the self-diffusion coefficient and the critical temperature T＊ = kT/ε = 1.25. The value of the self-diffusion coefficient strongly depends on system size. The data of the self-diffusion coefficient are fitted to a simple analytic relation based on hydrodynamic arguments. This correction scales as N-α, where α is an adjustable parameter and N is the number of particles. It is observed that the values of a 〈 1 provide quite a good correction to the simulation data. The system size dependence is very strong for lower densities, but it is not as strong for higher densities. The self-diffusion coefficient calculated with non-equilibrium molecular dynamic simulations at different temperatures and densities is in good agreement with other calculations fronl the literature.展开更多
采用非平衡分子动力学模拟的方法探究了石墨烯层数对石墨烯/聚乙烯复合材料界面热导的影响。结果表明,随着石墨烯层数的增大,界面热导呈现较小的增长趋势。通过分析石墨烯碳原子与聚乙烯碳原子间的振动能谱(vibration power spectra,VPS...采用非平衡分子动力学模拟的方法探究了石墨烯层数对石墨烯/聚乙烯复合材料界面热导的影响。结果表明,随着石墨烯层数的增大,界面热导呈现较小的增长趋势。通过分析石墨烯碳原子与聚乙烯碳原子间的振动能谱(vibration power spectra,VPS)探究了石墨烯层数影响的内在机理。结果发现,石墨烯碳原子低频范围(<50THz)的振动模式主要影响界面的热传输。展开更多
Both ionic solutions under an external applied static electric field E and glassy-forming liquids under undercooled state are in non-equilibrium state.In this work,molecular dynamics(MD)simulations with three aqueous ...Both ionic solutions under an external applied static electric field E and glassy-forming liquids under undercooled state are in non-equilibrium state.In this work,molecular dynamics(MD)simulations with three aqueous alkali ion chloride(NaCl,KCl,and RbCl)ionic solutions are performed to exploit whether the glass-forming liquid analogous fractional variant of the Stokes–Einstein relation also exists in ionic solutions under E.Our results indicate that the diffusion constant decouples from the structural relaxation time under E,and a fractional variant of the Stokes–Einstein relation is observed as well as a crossover analogous to the glass-forming liquids under cooling.The fractional variant of the Stokes–Einstein relation is attributed to the E introduced deviations from Gaussian and the nonlinear effect.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 51076128)the National High Technology Research and Development Program of China (Grant No. 2009AA05Z107)
文摘We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with temperature decreases by increasing density. For density ρ＊ = ρσ3 = 0.84 we observe a peak at the value of the self-diffusion coefficient and the critical temperature T＊ = kT/ε = 1.25. The value of the self-diffusion coefficient strongly depends on system size. The data of the self-diffusion coefficient are fitted to a simple analytic relation based on hydrodynamic arguments. This correction scales as N-α, where α is an adjustable parameter and N is the number of particles. It is observed that the values of a 〈 1 provide quite a good correction to the simulation data. The system size dependence is very strong for lower densities, but it is not as strong for higher densities. The self-diffusion coefficient calculated with non-equilibrium molecular dynamic simulations at different temperatures and densities is in good agreement with other calculations fronl the literature.
文摘采用非平衡分子动力学模拟的方法探究了石墨烯层数对石墨烯/聚乙烯复合材料界面热导的影响。结果表明,随着石墨烯层数的增大,界面热导呈现较小的增长趋势。通过分析石墨烯碳原子与聚乙烯碳原子间的振动能谱(vibration power spectra,VPS)探究了石墨烯层数影响的内在机理。结果发现,石墨烯碳原子低频范围(<50THz)的振动模式主要影响界面的热传输。
基金Project supported by the Science Foundation of Civil Aviation Flight University of China(Grant Nos.J2019-059 and JG2019-19)。
文摘Both ionic solutions under an external applied static electric field E and glassy-forming liquids under undercooled state are in non-equilibrium state.In this work,molecular dynamics(MD)simulations with three aqueous alkali ion chloride(NaCl,KCl,and RbCl)ionic solutions are performed to exploit whether the glass-forming liquid analogous fractional variant of the Stokes–Einstein relation also exists in ionic solutions under E.Our results indicate that the diffusion constant decouples from the structural relaxation time under E,and a fractional variant of the Stokes–Einstein relation is observed as well as a crossover analogous to the glass-forming liquids under cooling.The fractional variant of the Stokes–Einstein relation is attributed to the E introduced deviations from Gaussian and the nonlinear effect.
