▎ 摘　　要

According to the Mermin-Wagner theory and the elasticity theory, people have considered the strictly two-dimensional crystalline material could not exist that was completely negated by the discovery and the preparation of two-dimensional graphene films. Up to now, whether graphene is an ideal two-dimensional planar structure in natural state has yet to be further confirmed. At room temperature (300 K), based on Tersoff-Brenner potential and AIREBO potential, some molecular dynamics simulations were carried out to study the relaxation characteristics of three kinds of single layer graphene nanoribbons with different aspect ratios, respectively. The simulation results indicate that the single layer graphene nanoribbons at room temperature is not a perfect planar structure and that a certain degree of fluctuates and folds occur at the edges and inner region of nanoribbons, which are consistent with the existing experimental results; the surface fluctuates level of graphene nanoribbons decreases along with the increase of the nanoribbons' size. For the same size of graphene nanoribbon, the system kinetic energy at room temperature is much higher than that at ideal temperature (0.01 K), and thus a dramatic influence on the relaxation deformation of the graphene nanoribbons will happen, which indicates that the higher the system temperature, the greater the deformation.