APPLICATION OF RIGID-BODY DYNAMICS AND SEMICLASSICAL MECHANICS TO MOLECULAR BEARINGS

Various types of molecular bearings, gears, joints, etc have recently been proposed and studied in the growing nanotechnology literature usi ng classical molecular dynamics. In a previous study, we reported simu lations for several model graphite bearings using fully atomistic mole cular dynamics simulations. It was subsequently found that various pre dictions based on simulations of this type do not agree with those of a more correct quantum approach owing to leakage of the quantum zero-p oint vibrational energy in the molecular dynamics simulations. In this study we use the tools of rigid-body dynamics to address the zero-poi nt energy problem. The results of these simulations are striking in th e sense that under certain conditions the bearing is found to be frict ionless, as previously alluded to by Feynman. A frictionless bearing w ill undergo 'superrotation', a classical dynamical behavior reminiscen t of superfluidity. States which are chaotic in nature may not have th is new characteristic, an issue we investigate with maps of phase spac e.