Molecular motion under stochastic gating

We investigate molecular passage through a geometrical barrier. We assume that the barrier is a stochastic gate so that the passage rate depends on its fluctuating nature and on the molecular size. We calculate the dependence of the passage rate K_effon relaxation rate of the gate radius and therefore on the solvent viscosity η. Two cases are solved: an open-or-closed gate and an harmonic gate. The latter is shown to lead to the experimentally observed fractional power law dependence of K_effon η.