Nanomachinery: A general approach to inducing directed motion at the atomic level

The motion of bodies in a periodic potential relief with weak attenuation is considered. When subjected to various periodic external effects, the bodies may spontaneously move with a velocity uniquely defined by the frequency of a periodic action and the space period of the potential. Principles of inducing directed motion with a strictly controllable velocity that are described in this paper can be used for (1) handling individual molecules or molecular clusters on crystal surfaces, (2) creating nanomachines—objects that are free to spontaneously move both in the absence of an external force and in the presence of a force opposite to the direction of motion (and thus capable of transporting other objects), (3) designing actuators providing a strictly controllable velocity of motion, and (4) designing controllable tribological systems by appropriately profiling tribosurfaces and applying ultrasonic actions. Under periodic external perturbations, the dependence of the mean velocity of a system on the mean applied force (which macroscopically appears as the “friction law” for the system) is shown to contain plateaus of constant velocity not only when the velocity of motion is zero but also when a set of discrete equidistant velocities is present. The problem of creating totally controllable nanomachines can be posed as the problem of controlling the width and position of these plateaus.