应变石墨烯纳米带谐振特性的分子动力学研究

Molecular dynamics simulation of resonance properties of strain graphene nanoribbons

从动势能转换与守恒原理出发,在微正则(NVE)系综下,采用COMPASS力场对石墨烯纳米带及其应变传感器的谐振特性进行了分子动力学模拟.研究发现,非线性响应主导了石墨烯纳米带的动态行为,而其超高的基波频率则与长度和边界条件密切相关;单轴拉伸应变对石墨烯纳米带基波频率的影响显著且强烈依赖于边界条件,四边固支型应变石墨烯纳米带具有更高的频移,其灵敏度可高达7800Hz/nanostrain,远大于相同长度碳纳米管应变传感器的灵敏度;石墨烯纳米带及其应变传感器的谐振特性均与手性无关.本文所得结果表明,由于超低的密度、超高的基波频率与灵敏度且无需考虑手性的影响,通过适当地裁剪尺寸和设定边界条件,石墨烯纳米带可用于设计新一代的纳机电系统(NEMS)高频谐振器与应变传感器.

Starting from the energy conversion and energy conservation law in the constant-NVE ensemble,the molecular dynamics method using the COMPASS force field was applied to investigate the dynamic properties of graphene nanoribbons（GNRs） together with the GNR-based strain sensors.The following results were obtained（a） the nonlinear response dominates the dynamic behavior of GNRs,and their ultra-high fundamental frequencies are closely related with the length and boundary conditions;（b） the effect of uniaxial tensile strain on the fundamental frequencies of GNRs is significant and strongly depends on boundary conditions,and the GNR-based strain sensor clamped on four edges has a higher frequency shift,and its sensitivity is up to 7800 Hz /nanostrain,much higher than that of carbon nanotube-based strain sensor with the same length;（c） the resonant characteristics of GNRs and GNR-based strain sensors are insensitive to the chirality.The obtained results suggest that,through cutting the appropriate size and setting the boundary conditions,the GNRs could be used to design a new generation of nanoelectromechanical system（NEMS） resonators and strain sensors,owing to their ultra-low density and ultra-high fundamental frequencies as well as ultra-high sensitivity without considering the impact of chirality.