Studies On Dislocation Motion Of Graphene

Graphene becomes a hot research topic of modern science for its distinctive electronic properties and potential applications.Like in the three dimensional crystal,structure defects in graphene have an important impact on the physical properties,for example,point defect and replacement dislocation have an important influence on graphene's electrical and mechanical properties.So the generation and motions of the dislocation in graphene are very important.Dislocation motion can be considered as the conformational change of a molecule,that is graphene changes from a stable state to another stable state.During conformational change,it is hard to seize the transition state in the experiment,because the probability is very low and the life time of the transition state is very short.However,computer simulation can find the transition state.The widely used computing simulation method includes string method,NEB(nudged elastic band)method,path sampling method,etc.The most typical dislocation in graphene is Stone Wales(SW)defect.In this thesis,two motions of SW defect are simulated.One is the generation of SW defect.The other is the slip of SW defect,that is SW defect changes the position.In addition,the slip of Shuffle dislocation in graphene is studied.The minimum energy paths of these dislocation motions are obtained using NEB method,and the energy barriers and transition states of these dislocation motions are given through analyzing the energies of the minimum energy paths.The results show that the energy barrier of the slip of Shuffle dislocation is smaller than that of SW defect,so Shuffle dislocation slips more easily than SW defect.