  In this paper we investigate the effects of graphene nanopore geometry on
homopolymer ssDNA pulling process through nanopore using steered molecular
dynamic (SMD) simulations. Different graphene nanopores are examined including
axially symmetric and asymmetric monolayer graphene nanopores as well as five
layer graphene polyhedral crystals (GPC). The pulling force profile, moving
fashion of ssDNA, work done in irreversible DNA pulling and orientations of DNA
bases near the nanopore are assessed. Simulation results demonstrate the strong
effect of the pore shape as well as geometrical symmetry on free energy
barrier, orientations and dynamic of DNA translocation through graphene
nanopore. Our study proposes that the symmetric circular geometry of monolayer
graphene nanopore with high pulling velocity can be used for DNA sequencing.
