Density functional study of the metallization of a linear carbon chain inside single wall carbon nanotubes

By means of the density functional theory, we studied the relaxed structure and electronic properties of new one-dimensional carbon nanostructures conformed by a linear carbon chain (LCC) inside (5,5) and (8,0) single-walled carbon nanotubes (SWCNTs). The calculations were performed with a linear combination of atomic orbitals method using pseudopotentials and the generalized gradient approximation for the exchange–correlation potential. We analyzed the atomic structure, band structure, and the local density of states. We found that, despite the fact that LCC and (8,0) SWCNT have a band gap, the system LCC@(8,0) shows a metallic character. This metallic behavior is provided by the electronic states from the LCC exclusively, due to charge transfer from carbon nanotube to the LCC. However, the electronic characters of the nanotubes in LCC@SWCNT are the same as that of isolated SWCNTs.