The dynamics of molecular bearings

Various types of molecular bearings have recently been proposed in the growing nanotechnology literature. Using novel molecular dynamics methods, we have simulated several model graphite bearings. The bearings varied in size from inner shafts of between 4 and 16 A in diameter, up to 120 A in length, and outer cylinders of between 10 and 23 A in diameter, up to 40 A in length. The turning shaft was either instantaneously started or torqued up to the desired rotational speeds. Frictional properties were size-, temperature- and velocity-dependent. The presence of more than one bearing vibrational mode in some simulations created beats that could possibly adversely affect bearing performance; placing a stretching tension on the bearing suppressed one of the modes and therefore the beats. These and future studies will help evaluate the performance, wear and load-bearing properties of fundamental components of nanomachines such as bearings.

[1]  Stephen K. Gray,et al.  Symplectic integrators for large scale molecular dynamics simulations: A comparison of several explicit methods , 1994 .

[2]  James Lewis,et al.  Nanotechnology : research and perspectives : papers from the First Foresight Conference on Nanotechnology , 1992 .

[3]  S. Iijima.  Helical microtubules of graphitic carbon , 1991, Nature.

[4]  M. S. de Vries,et al.  Cobalt-catalysed growth of carbon nanotubes with single-atomic-layer walls , 1993, Nature.

[5]  P. Ajayan,et al.  Large-scale synthesis of carbon nanotubes , 1992, Nature.

[6]  Bobby G. Sumpter,et al.  Molecular dynamics simulations of polymers: Methods for optimal Fortran programming , 1989 .

[7]  William G. Hoover,et al.  Nonequilibrium Molecular Dynamics , 1983 .

[8]  Stephen K. Gray,et al.  Novel methods for spectral analysis , 1991 .

[9]  Jawad Faiz,et al.  Simulation and analysis of brushless DC motor drives using hysteresis, ramp comparison and predictive current control techniques , 1996, Simul. Pract. Theory.

[10]  D. W. Noid,et al.  The existence of nonlinear resonances in collective modes of linear macromolecules , 1994 .

[11]  N. Hatta,et al.  Very long graphitic nano-tubules synthesized by plasma-decomposition of benzene , 1994 .

[12]  D. W. Noid,et al.  Molecular dynamics calculation of the density of states for poly(ethylene) : collective versus local modes , 1990 .

[13]  D. Weeks.  Isotopic and anharmonic perturbations to the dipole active vibrational modes of buckminsterfullerene , 1992 .

[14]  David E. Weeks,et al.  Rotation–vibration spectra of icosahedral molecules. II. Icosahedral symmetry, vibrational eigenfrequencies, and normal modes of buckminsterfullerene , 1989 .

[15]  William A. Goddard,et al.  Prediction of fullerene packing in C60 and C70 crystals , 1991, Nature.

[16]  Ralph C. Merkle,et al.  A proof about molecular bearings , 1993 .