Structural and electronic properties of ZnO nanotubes from density functional calculations

The structural and electronic properties of armchair and zigzag ZnO nanotubes were studied using density functional theory with the generalized gradient approximation. It was found that the strain energy required for rolling a ZnO graphitic sheet into a tube is lower than those for BN and GaN nanotubes. Both the armchair and zigzag ZnO nanotubes were found to be direct gap semiconductors with the gaps decreasing with the diameter increase.