Conformational and dynamical properties of semiflexible polymers in the presence of active noise

Abstract

Abstract. In the presence of active noise, flexible and semiflexible polymers exhibit drastically different conformational and dynamical features compared to the case of thermal (white) noise only. For a non-Markovian exponentially correlated temporal noise (colored noise), flexible polymers swell with increasing noise strength, whereas semiflexible polymers shrink first and, for larger noise strengths, swell similar to flexible polymers. Thereby, a suitable treatment of the finite polymer contour length is essential. The finite contour length implies a strong dependence of the polymer relaxation times on the noise strengths. We discuss the conformational and dynamical aspects in terms of an analytical model, adopting the continuous Gaussian semiflexible polymer description. Moreover, results of computer simulations are shown and compared with analytical results.

Active Brownian ring polymers

“…Hence, such models predict a different Péclet-number dependence than that derived by our approach even at moderate Pe. Note that our analytical results for linear polymers nearly quantitatively agree with simulation results of ABP polymers, 73 confirming the derived dependence on Pe and the saturation.…”

“…In particular, the segmental mean square displacement (MSD) of semiflexible polymers is slowed down and exhibits a time dependence similar to a passive flexible polymer at larger activities. 38 These findings are in qualitative 18,26,72 and even in quantitative 73 agreement with computer simulation results. Ring polymers, specifically flexible rings, exhibit a similar qualitative behavior, although there are quantitative differences mainly due to the distinct boundary conditions and the correspondingly different wave-number spectra.…”

“…in analogy to an ABP/AOUP. 74 This choice is motivated by a bead-spring polymer model as used in simulations of active polymers, 17,18,73 where l corresponds to the bead diameter (bond length). In the following, we set ∆ = 1/3, the value of a passive colloid in solution.…”

Active Brownian Filamentous Polymers under Shear Flow

“…For an identical mathematical formulation, the active site has then to be described by an active Ornstein–Uhlenbeck particle (AOUP) [73,83]. However, also an active Brownian particle (ABP) can be considered, as long as only second moments of the active velocity correlation function are relevant [57]. In any case, the active velocity is described by a diffusive process—Brownian motion—either for the propulsion direction only (ABPs) [4,5,6,10,84,85], or for the individual Cartesian components, i.e., the magnitude of v is changing too (AOUPs) [4,52,73,83].…”

“…In fact, active systems with internal degrees of freedom, such as linear chains [7,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54] or other forms of organization [33,34,55,56], denoted as “active colloidal molecules” in Ref. [34], are particularly interesting and give rise to novel conformational [39,41,47,52], dynamical [45,53,57,58,59], and collective phenomena [12,16,56,60,61,62,63,64,65,66]. Examples range from activity-induced polymer swelling and shrinkage [7,39,41,47,52], enhanced diffusive motion and dynamics [40,41,53,59]—as observed in microtubuli [67], actin filaments [68], chromosomal loci in simple organisms [69,70], or in the chromatin dynamics in eukaryotes [71]—to mesoscale turbulence [12,…”