Theoretical determination of the strength of soft noncovalent molecular bonds

Abstract

The strength of a simple soft bond under a constant loading rate is studied theoretically. There is a scaling regime where rebinding is negligible and the rupture force scales as $\mathrm{const}+{\left[\ln \left(kv\right)\right]}^{2∕3}$, where $kv$ is the loading rate. The scaling regime is smaller for weaker bonds and broader for stronger bonds. For a loading rate beyond the upper limit of the scaling regime, the bond rupture is deterministic and the thermal effects are negligible. For a loading rate below the lower limit of the scaling regime, the contribution from rebinding becomes important and there is no simple scaling relation between the rupture force and the loading rate. Our theory takes the effect of rebinding in the calculation, therefore we find good agreement between theory and simulation even below the scaling regime.