单空位缺陷对载能氢原子与石墨层间碰撞的能量交换的影响的分子动力学研究

Molecular dynamics simulation of energy exchange during hydrogen collision with graphite sheet containing a vacancy

本文采用分子动力学方法研究空位缺陷对石墨层中碳氢粒子碰撞的影响.将氢原子以不同能量分别向单空位缺陷边缘的两个碳原子轰击,分析了入射氢原子的能量损失、发生吸附反应的能量范围和靶原子的能量传递过程.研究发现,单空位缺陷边缘的碳氢粒子更易发生吸附反应;在碳氢粒子正碰过程中,氢原子随入射能量变化出现了双反射区域;碳氢粒子在空位缺陷边缘吸附后,形成了高结合能的sp2结构,并出现悬挂键,其临近的碳碳键能未降低;单空位缺陷边缘的碳原子吸附氢原子能量的能力强而传递能量的能力弱.这些结果对理解聚变反应中,碳基材料的化学腐蚀及氚滞留有重要意义.

Molecular dynamics simulation is applied to investigation of energy exchanges during hydrogen collision with graphite sheet containing a vacancy.The effects of the monovancancy defect on the energy exchanges are discussed in detail.This paper analyzes the energy loss of the incident hydrogen atom,the energy range for the adsorption process,and the energy transfer process for target atom,in the course of a hydrogen atom bombarding the carbon atom at the edge of monovacancy defect in the graphite sheet.The simulation results show that the adsorption process proceeds more easily when the graphite sheet contains a vacancy than when the graphite sheet has perfect crystalline structure.In certain areas of the graphite sheet,adsorption of an incident hydrogen atom can occur in two energy ranges.The sp2 structure as well as overhang configuration occurs when a hydrogen atom is adsorbed.This adsorption process does not reduce the C—C bond energy.It is found that the carbon atom at the edge of monovacancy defect can adsorb an incident hydrogen atom more easily but can not diffuse the gained energy as efficiently as in a perfect graphite sheet.These results are helpful for understanding the chemical erosion of carbon based materials and the ensuing tritium retention in fusion devices.