Dark Soliton Excitations in Single Wall Carbon Nanotubes

Dark soliton excitations are shown to exist in single wall carbon nanotubes (SWCNTs). At first, the nonlinear effective interatomic potential and the difference equation for longitudinal lattice displacement are obtained for the SWCNTs by expanding Brenner's many-body potential in a Taylor series up to fourth-order terms. Then using a multi-scale method, for short wavelength lattice excitations the equation of motion of lattice is reduced to the cubic nonlinear Schrodinger equation. Finally, the dark soliton solutions and relevant excitations in the SWCNTs with subsonic velocity are discussed.