The Collective Behavior of Semi-Flexible Active Polymers

Speaker: Twan Hooijschuur

Abstract:

Active filaments are fundamental to many biological systems, from motor-driven chromosomal DNA to actin filaments providing cellular structure and even worms crawling through soil. Their elongated shape introduces unique properties to active matter systems, where variations in length and flexibility can give rise to novel collective phenomena. Using molecular dynamics simulations, we investigated the collective behavior of semi-flexible active polymers across different densities, activity levels, and flexibilities. In a three-dimensional system, increasing density drives a transition from isotropic to globally ordered nematic phases. We examined how activity influences this transition and explored emergent behaviors at high activity levels, including local nematic order and turbulence-like motion. We find that low activity levels shifts the density of isotropic-nematic transition to higher densities, whereas high activity levels suppress the isotropic-nematic transition resulting in emergence of bending instabilities in the local nematic field and swirls in the velocity field.

Non-equilibrium steady states and transition rates of active particles in a double-well potential

Speaker: Vito Seinen

Abstract:

Active matter systems, which are composed of matter that is self-driven, have become a popular platform for exploring nonequilibrium steady states (NESS) due to their continuous energy injection and dissipation and the emergent behavior that result from it. In this work, we will investigate the steady states and transition rates of active Ornstein-Uhlenbeck particles (AOUP) and active Brownian particles (ABP) in double-well potential. We develop novel perturbative techniques allowing us to consider a wide range of activity strengths and persistence times. We will discuss our new insights obtained from our analytical calculations and numerical simulations on mean transition timed as a function of activity level and persistence time.

This seminar will take place in room C3.163