Fig. S5.

Transit time distributions from Brownian dynamics simulations. The transit times observed in simulations of diffusive motion over a 1D anharmonic energy profile similar to that in Fig. 4B (red) are longer than those (black) found for a harmonic energy profile having the same barrier height and curvature. The timescale for the exponential decay of the distribution for the anharmonic barrier increased 35% more than did the average transition path time, compared with the results for the harmonic barrier, leading to a discrepancy between D calculated from Eq. 1 versus Eq. 2 for the anharmonic barrier.