| Abstrakt: |
Rigid carbon nanotubes in single and double walled formations, placed on a graphite surface, are bounced, rotated, slid and rolled. Various features associated with these motions are studied by assuming a 6-exp form of interaction (Van der Waal's attraction and Born–Mayer repulsion) among the C-atoms. Calculations reported here are for tubes of diameter around 14 Å, for which rigid tube approximation is known to work well. The oscillatory motion corresponding to rolling has the softest mode, whereas the one with highest frequency corresponds to bouncing. The energy barriers corresponding to these motions are also reported in this paper. The rotational and translational energy barriers for the movement of one nanotube with respect to the other one, in a double walled nanotube, have also been studied and it turns out that these tubes rotate and slide freely at room temperature. The translational energy barrier, in case of zigzag tubes, is interestingly, an order of magnitude higher than that of armchair tubes. In case of rotation, the case is reverse. Furthermore, it turns out that any drag of a concentric nanotube along the long axis direction is coupled with rotation, indicating easy screw motion instead of a simple drag. We also describe the dynamics of translational telescopic motion of a multiwalled nanotube assembly where a core oscillates within an open ended outer shell assembly. [ABSTRACT FROM AUTHOR] |
