We propose a numerical approach to quantify the control of a nonautonomous molecular rotor motion. Unlike straightforward molecular dynamics simulations in an explicitly time-dependent framework, our method is based on the theory of geometric phases. This theory allows us to define a sensitivity field (SF) in control parameter space that characterizes average motion of a molecule induced by a cyclic perturbation. We show that the SF can be obtained using only equilibrium free energy sampling techniques. A density plot of the SF quantifies response of a molecule to an arbitrary cyclic adiabatic evolution of parameters. For demonstration, we numerically find the SFs for two surface mounted molecular rotor molecules that can be driven, in practice, by strong time-dependent electric fields of a STM tip.
© 2011 American Institute of Physics