  We consider the classical response in a chaotic system. In contrast to
behavior in integrable or almost integrable systems, the nonlinear classical
response in a chaotic system vanishes at long times. The response also reveals
certain features of collective resonances which do not correspond to any
periodic classical trajectories. The convergence of the response is shown to
hold due to the exponential time dependence of the stability matrix. The
growing exponentials corresponding to strong instability do not inhibit the
convergence. We calculate both linear and second-order response in one of the
simplest chaotic systems: free classical motion on a surface of constant
negative curvature. We demonstrate the relevance of the model for applications
to spectroscopic experiments.
