Abstract
A nonequilibrium molecular-dynamics method of computing the dynamical response is presented. It is applied to the mobility of a charged particle in a Lennard-Jones liquid and the results agree with those computed from the Green-Kubo formula and with experimental data on argon. A discussion is given of the linearity of the mechanical response. The linear-response term is evaluated explicitly by a perturbation formula and the character of the nonlinear terms is briefly considered.