Figure 2.

MFPT in dependence of the second barrier height, ΔU₂, calculated by using the Kramers’ ansatz (———), and approximation of the barrier transitions by rate constants. For transitions from the initial state to the intermediate across ΔU₁, the rate is denoted by k₁ whereas the escape rate from the intermediate in the forward and the backward direction is given by k₂. The inverses of the rate constants 1/k₁ (– · – · –) and 1/k₂ (·····) are shown as well as the inverses of the eigenvalues of the overall system 1/λ₁ (– – – –). As a reference, the MFPT of a single barrier crossing is also shown as a horizontal line at MFPT = 2,550. The inset zooms on the second barrier height, ΔU₂, within 1 k_BT. The boundary conditions and the units are described in Fig. 1.