Target Search of a Polymer with an Active Head

Abstract

We employ computer simulations to study the dynamics and target search of a spherically confined polymer, where one terminal monomer, referred to as the ``head'' is modeled as an active Brownian particle, while the remaining monomers are passive, and form a tail. As the activity of the head monomer is increased, the dynamics of the polymer is enhanced, enabling the head to reach the surface of spherical confinement. Eventually, it finds the pore (target) and escapes. In contrast, a passive polymer exhibits slower dynamics, as a result, the head monomer is unable to find the pore. To quantify this behavior, we compute the mean search time, the average time taken for the active head to reach the pore. Our results reveal that by increasing the activity of the head, the mean search time decreases for a given chain length. Interestingly, when the activity is low, the longer chain takes less time to find the pore, compared to a shorter chain. However, at higher activity, the mean search time for all chain lengths becomes similar and approaches that of an active Brownian particle (ABP). Also, bending rigidity reduces the mean search time. In addition, the mean search time decreases with the radius of spherical confinement. Furthermore, we find that fluctuations in search times are minimal at both low and high activity. Our in silico investigation depicts the dependence of the mean search time on factors such as activity, chain length, bending rigidity, and the radius of spherical confinement.