Phonons in graphitic tubules: A tight-binding molecular dynamics study

Using the tight binding molecular dynamics method (TBMD), the structural and dynamical properties of graphitic tubules are studied. The phonon dispersion and density of states of graphitic tubules with various helicities and diameters are calculated. Phonon modes in tubules are softened by the curvature when compared with graphite. Unique features of the graphitic tubule, with special emphasis on low-frequency modes, are discussed. The symmetry of phonon modes is analyzed, and infrared and Raman active modes are identified. Sound velocities in graphitic tubules are also calculated as functions of tubule helicity and diameter. © 1995 American Institute of Physics.