Nonlinear noninertial response of a Brownian particle in a tilted periodicpotential to a strong ac force

The solution of the Langevin equation describing the dynamics of a Brownian particle in a tilted periodic potential in the overdamped limit is obtaine d in terms of a matrix continued fraction, allowing us to evaluate statisti cal averages governing the nonlinear response to a strong ac force. Pronoun ced nonlinear effects are observed for large values of the ac force. For a weak ac force and low noise strength, the results obtained agree closely wi th previously available linear response and noiseless solutions, respective ly.