Figure 1.

Rupture characteristics obtained numerically using a potential with two barriers at constant loading rates. (a) U(x) (magenta) and U(x) − f · x (cyan) with A = 5 pN nm and f = 50 pN. Reflecting and absorbing boundary conditions are set at x = a and x = b, respectively. (b) Rupture force distributions, $P\left(f\right)=k\left(f\right)/r_f·\exp [-{\int }_0^{f}d{f}^{\prime }k\left(f^{\prime }\right)/r_f]$, at varying r_f were computed by using mean first passage time (MFPT), $k^{-1}\left(f\right)=D^{-1}{\int }_a^{b}dy{e}^{\beta \left(U\right(y)-f·y)}{\int }_a^{y}dz{e}^{-\beta \left(U\right(z)-f·z)}$, starting from the first bound state at a(=0 nm) to reach an absorbing boundary at b(=5 nm). MFPT expression is valid in the force regime where stationary flux approximation holds.⁴ The length was scaled by nm, and D = 1.0 × 10⁷ nm²/s was used for the diffusion constant. (c) [f^*, log r_f] plots at three A values. Fits of [f^*, log r_f] to Eq. 5 yield ν ≪ 0.5 for all A values (ν = 0.064, 0.075, 0.046 for A = 4, 5, 6 pN nm, respectively). In this case, the data should be divided into two regions and analyzed by the two linear fits as depicted using green lines on the curve with A = 6 pN nm. (d) Loading rate dependent x^‡(r_f) (= x_ts − x_b), extracted from the slope of plot at each r_f in (c) with A = 5 pN nm, shows a sharp decrease from ∼3 nm to <1 nm around r_f ≈ (e⁻³ − e⁰) pN/s.