C-57 nanotube: electronic, optical, and mechanical properties by DFT calculations

Abstract

Electronic, optical, and mechanical properties of single-walled C-57 carbon nanotube have been investigated within the framework of density functional theory (DFT). It was found that for the nanotube, there is a direct relationship between its radius and Young’s modulus: larger radius leads to larger Young’s modulus. Optical properties have been calculated within a NORMCONS pseudopotential type (Von Barth–Car Method) whit Perdew–Zunger (LDA) exch-correlation scalar relativistic functional type, showing that decrease in radius of the nanotube increases both static refractive index and dielectric constant is increased. Examining band structure and density of states (DOS) further reveals that this nanotube is a metallic carbon allotrope. The potential ability of lithium (Li) and sodium (Na) adsorption on single-layer C-57 nanotube has also been evaluated at vdW-DF3-OPT2, PBEsol and DFT-D3 levels of theory. Preferred Li or Na adsorption sites have accordingly been identified in terms of adsorption energy; and geometries of 1 up to 4 adsorbed Li or Na atoms on the outside of the nanotube was also studied. Results of the adsorption energy and the open circuit voltage (OCV) showed that this nanostructure could be a suitable material for lithium or sodium storage. In addition, suitable theoretical storage capacity (278.92 mAh g−1) was obtained as an anode material.