Self-attractive semiflexible polymers under an external force field

TL;DR

This study investigates how self-attractive semiflexible polymers in two dimensions respond dynamically to external forces, revealing conformational transitions and force-dependent deformation behaviors through numerical simulations.

Contribution

It provides new insights into the force-induced conformational changes of self-attractive semiflexible polymers, highlighting the effects of stiffness and self-interaction strength.

Findings

Strong self-attraction leads to diverse equilibrium structures.

External force causes continuous unwinding of flexible chains.

Stiffer double-stranded conformations exhibit sharp unfolding transitions.

Abstract

The dynamical response of a tethered semiflexible polymer with self-attractive interactions and subjected to an external force field is numerically investigated by varying stiffness and self-interaction strength. The chain is confined in two spatial dimensions and placed in contact with a heat bath described by the Brownian multiparticle collision method. For strong self-attraction the equilibrium conformations range from compact structures to double-stranded chains, and to rods when increasing the stiffness. Under the external field at small rigidities, the initial close-packed chain is continuously unwound by the force before being completely elongated. For double-stranded conformations the transition from the folded state to the open one is sharp being steeper for larger stiffnesses. The discontinuity in the transition appears in the force-extension relation as well as in the probability distribution function of the gyration radius. The relative deformation with respect to the equilibrium case along the direction normal to the force is found to decay as the inverse of the applied force.