Atomic and electronic structure of rigid carbon atomic chains

We have reported, from ab initio calculations, on the changes in the electronic and structural properties of short carbon atomic chains held rigidly between hydrogenated armchair graphene nanoribbons (AGNR) and zig-zag graphene nanoribbons (ZGNR). Several lengths (N?=?29 atoms) and forms of the chains have been considered. All models are found to be metallic in nature, with chemical bonding more like $\cdots {\rm C}- {\rm C}\equiv {\rm C}- {\rm C}\equiv {\rm C}\cdots $ (as in polyyne) for odd-numbered chains and $\cdots {\rm C} = {\rm C} = {\rm C} = {\rm C}\cdots $ (as in cumulene) for even numbered chains. An examination of the variation of the density of states (DOS) near the Fermi level with chain length suggests the possibility for tunability of the metallic property of short carbon chains