尺度效应下太赫兹非局部二维纳米薄膜结构涟漪动力学建模方法

Modeling Method for the Dynamics of Ripples in Terahertz Nonlocal Two-Dimensional Nanofilm Structures Considering Scale Effects

本研究通过非局部理论和分子动力学模拟,深入探讨了尺度效应下二维纳米薄膜涟漪动力学特性.首先,基于非局部Kirchhoff板理论,构建了太赫兹激励下二维纳米薄膜涟漪动力学模型,揭示了涟漪波数与太赫兹激励频率的关系.其次,通过与分子动力学模拟对比,验证了非局部涟漪动力学模型的准确性,并对非局部参数进行了辨识.进一步,分析了小尺度范围下二维薄膜结构离散分子动力学模型和连续介质理论模型的差异性,讨论了等效厚度,手性和非局部参数等重要参数对涟漪波数和相速度的影响.研究表明:当涟漪波长接近碳-碳键尺度时,原子的离散特性破坏了相邻涟漪的均匀性,论证了考虑原子分布的离散特性对太赫兹高频激励下二维纳米薄膜跨尺度涟漪动力学建模的重要性.此外,本研究还发现了锯齿方向的相速度大于扶手椅方向的相速度,且随着中心激励频率的增加,闭合涟漪的波型从环形转变为六边形.

This study delves into the dynamic characteristics of ripples in two-dimensional(2D)nanofilms considering scale effects through nonlocal theory and molecular dynamics simulations.Initially,ripple dynamics model for 2D nanofilms under terahertz(THz)excitation is constructed based on the nonlocal Kirchhoff plate theory,revealing the relationship between ripple wavenumber and THz excitation frequency.Subsequently,the accuracy of the nonlocal ripple dynamics model is verified by comparing it with molecular dynamics simulations,and the nonlocal parameters is identified.Furthermore,the differences between the discrete molecular dynamics model and the continuous medium theory model for 2D film structures at small scales is analyzed,and the effects of important parameters such as equivalent thickness,chirality and nonlocal parameters on ripple wavenumber and phase velocity is discussed.The study indicates that when the ripple wavelength approaches the scale of carbon-carbon bonds,the discrete nature of atoms disrupts the uniformity of adjacent ripples,demonstrating the importance of considering the discrete nature of atomic distribution for modeling the cross-scale ripple dynamics of 2D nanofilms under high-frequency THz excitation.Additionally,it is found that the phase velocity in the zigzag direction is greater than that in the armchair direction,and as the central excitation frequency increases,the wave pattern of closed ripples transitions from circular to hexagonal.