Structural and electronic properties of linear carbon chains encapsulated by flattened nanotubes

In the present contribution it was investigated the structural and electronic properties of nanostructures formed by a linear carbon chain encapsulated by flattened carbon and boron nitride single-walled nanotubes, using first-principles calculations. The behavior of the atomic structure and the corresponding electronic properties of the nanostructures were systematically analyzed as a function of the tube flattening degree. For both types of nanotubes, it was detected the occurrence of a polyyne-cumulene transition, which depends on the flattening degree. Moreover, for carbon nanotubes, it was found, for strong flattening, that the carbon chain binds completely to the tube wall. However, for boron nitride nanotubes, the chain also binds to the tube wall, but it breaks into pieces. For each structure, the electronic behavior and the band structure was studied as a function of the tube deformation. For particular values of the flattening degree it was observed the occurrence of Dirac points. The calculated Fermi velocities are in good agreement with the values obtained for graphene. (C) 2016 Elsevier B.V. All rights reserved.