Quasiadiabatic solutions of Fokker Planck equations with time-dependent drift and fluctuations coefficients

A systematic algorithm for finding solutions of Fokker Planck systems with time-dependent drift and fluctuation coefficients is developed. The solutions lag behind the adiabatic quasistationary distribution. This delay effect vanishes for slowly varying control parameters. In a first example the evolution of the phase transition from a monostable to a bistable system is treated. There is a fluctuation enhancement and the delay of the probability distribution leads to a transient central peak. In a second example a linear model with time-dependently shifted drift is considered. The introduced approximation scheme reproduces the exact solution already in first order.