Structural stability of carbon nanosprings

A carbon nanospring is formed by coiling a single-walled carbon nanotube (n, m) surrounding a cylinder surface with a uniform pitch length and spring rising angle. Both armchair and zigzag carbon nanosprings are studied. Due to the limitations of hexagonal carbon-atom rings and the bond length of carbon–carbon atoms, a maximum rising angle exists for each type of nanospring (n, m), and zigzag nanosprings have greater maximum rising angles than armchair nanosprings with the same spring radius. In this study, a molecular mechanics (MMs) calculation is performed to investigate the structural properties of carbon nanosprings. Flat carbon nanosprings are obtained with small spring radii and rising angles, and round carbon nanosprings are found to have a larger spring radius than flat ones. The results show that the structural stability of a nanospring mainly depends on the parameters of its tube radius, spring radius, and rising angle, whereas its chiral type has little effect.