What Is Armchair-Zigzag Grain Boundary Structure in Graphene?

We have developed a new global optimization method for the determination of interface structure based on the differential evolution algorithm. Here, we applied this method to search for the ground state atomic structures of the grain boundary between the armchair and zigzag oriented graphene. We find two new grain boundary structures with considerably lower formation energy of about 1 eV/nm than that of the previously widely used structural models. These newly predicted structures show better mechanical property under external uniaxial strain, and distinguishable scanning tunneling microscope features, compared with the previous structural models. Our results provide important new information for the determination of grain boundary structures and henceforth the electronic properties of defected graphene.