Zigzag graphene nanoribbons with curved edges

Zigzag-edged single and double folded graphene nanoribbons are studied using density functional theory methods. Some asymmetric folds and folds with an octagon/hexagonal extended defect line are also considered. The long-range van der Waals interactions are taken into account viasemiempirical pairwise optimized potential. The geometrical and magnetic phases of the studied structures are obtained. It is shown that the magnetic states of the folds depend strongly on their stacking patterns. The electronic structures in terms of energy needed for the folding process, van der Waals contribution, energy band gaps, band structures, and densities of states are also calculated. We find that significant changes in the electronic structure can be achieved as a result of folding and adding line defects.