载能碳离子撞击石墨烯中Stone-Wales缺陷的动力学研究

采用分子动力学模拟方法,研究了载能碳离子撞击石墨烯中Stone-Wales缺陷的动力学过程,计算了Stone-Wales缺陷中初级碰撞原子的离位阈能和载能碳离子使其移位的入射阈能,并与完美石墨烯结构计算结果进行对比。通过分析初级碰撞原子与入射离子动能和势能随时间的变化关系,研究了碰撞过程中能量转移过程。研究结果表明,初级碰撞原子产生离位并最终脱离石墨烯体系的最小能量为25.0 eV。当初始动能为23.0 eV时,Stone-Wales缺陷中2个七元环共用的碳-碳键旋转90°形成了完美的石墨烯结构。此外,还发现使Stone-Wales缺陷中初级碰撞原子发生离位的载能碳离子最小入射能为41.0 eV。

Simulation Study of Collision Dynamics of an Energetic Carbon Ion to the Stone-Wales Defect Site in Graphene

The collision dynamics processes of an energetic carbon ion to the Stone-Wales defect in graphene are investigated by using molecular dynamics method. We calculate the displacement threshold energy for the primary knock-on atom in Stone-Wales defect and the incident threshold energy for the projectile carbon ion prompting the target atom displacement, which are compared with the results of the perfect graphene. The energy transfer is studied by analyzing the time evolutions of the kinetic energies and potential energies of the primary knock-on atom and the incident ion. We find that the displacement threshold energy is 25.0 eV, which is the minimum kinetic energy for the primary knock-on atom to leave its original position and eventually escape from the graphene system. When the initial kinetic energy is 23.0 eV, the common C-C bond of the two heptagons in the Stone-Wales defect rotates 90° to form a perfect graphene structure. The minimum incident energy of the projectile required to drive the primary knock-on atom in the Stone-Wales defect to displace permanently from its original location is 41.0 eV.