▎ 摘　　要

Generation mechanism of energy gaps between conductance and valence bands is at the centre of the study of graphene material. Recently, Chamon, Jackiw et al. proposed a mechanism of using a Kekule distortion background field phi and its induced gauge potential A(i) to generate energy gaps. In this paper, various vortex structures inhering in this model are studied. Regarding phi as a generic background field rather than a fixed Nielson-Oleson type distribution, we have found two new types of vortices on the graphene surface-the velocity field vortices and the monopole-motion induced vortices-from the inner structure of the potential A(i). These vortex structures naturally arise from the motion of the Dirac fermions instead of from the background distortion field. (C) 2009 Elsevier Inc. All rights reserved.