Molecular-dynamical studies of the depinning of charge-density waves

It is shown that a pure, classical insulating many-body system will exhibit nonlinear threshold behavior of the form ${(E-E_T)}^{\frac{1}{2}}$, where $E$ is the applied and $E_T$ is the threshold electric field. Evidence is presented, based on molecular dynamics calculations on a model for sliding charge-density waves in an impure lattice, that the current versus field curve will become concave upward, but will still have a well defined threshold field in the thermodynamic limit in qualitative agreement with experiment. It is speculated that the low-frequency noise found by Fleming and Grimes is due to the depinning and motion of a hierarchy of soliton lattices of large lattice constant which appear in any incommensurate system.