▎ 摘　　要

The migration of a single vacancy (SV) defect in graphene fragment (GF) has been investigated by density functional theory (DFT). The results revealed that a single vacancy defect is easy to migrate to the GF edge. The interaction between an SV and a five-numbered ring at the edge results in two neighboring five-membered rings finally, while the interaction between an SV and a seven-membered ring defect at the edge of the GF leads to a five-numbered ring and a neighbor seven-numbered ring. Our findings shed light upon understanding of the growth process of the graphene grain boundary. (C) 2015 Elsevier B.V. All rights reserved.