Self-avoiding walks adsorbed at a surface and pulled at their mid-point

TL;DR

This paper studies how the force needed to detach a self-avoiding walk from a surface varies depending on whether the force is applied at the middle or end, revealing location-dependent desorption behavior relevant to single molecule experiments.

Contribution

It introduces a model analyzing the effect of force application point on desorption of adsorbed walks, highlighting differences in temperature dependence.

Findings

Critical force depends on the point of application.

Desorption behavior varies with force application location.

Insights relevant for single molecule pulling experiments.

Abstract

We consider a self-avoiding walk on the $d$-dimensional hypercubic lattice, terminally attached to an impenetrable hyperplane at which it can adsorb. When a force is applied the walk can be pulled off the surface and we consider the situation where the force is applied at the middle vertex of the walk. We show that the temperature dependence of the critical force required for desorption differs from the corresponding value when the force is applied at the end-point of the walk. This is of interest in single molecule pulling experiments since it shows that the required force can depend on where the force is applied. We also briefly consider the situation when the force is applied at other interior vertices of the walk.