Collective and tracer dynamics in single-file transport through periodic structures

• Applicant: Professor Dr. Philipp Maass
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 432123484

• Final Report Year: 2024

Final Report Abstract

In this research project, Brownian single-file motion of particles through narrow periodic structures is studied, where particles cannot overtake each other because of their interactions and spatial confinements. Single-file motion occurs, for example, in zeolites, membrane pores, nanotubes, channels in micro- and nanofluidic devices, and experiments with colloidal particles, where periodic potentials can be generated in a controlled way by optical and magnetic manipulation techniques. One key finding of the studies performed in the project is that solitary cluster waves occur in systems of hard spheres at high particle densities. These solitons are periodic movements of particle clusters. In the clusters, particles touch each other or are nearly in contact. At low temperatures, the solitons form around magic hard-sphere diameters only, which are certain rational fractions of the wavelength of the periodic potential. The solitons mediate transport of particles even if single particles cannot surmount potential barriers much higher than the particles’ thermal or mean kinetic energy. We developed a theory to explain the formation of the solitons, and to describe their properties, including soliton propagation modes, soliton velocities, and soliton-mediated particle currents. The soliton velocities turned out to be orders of magnitude higher than the mean velocity of a single particle in the periodic potential. At higher temperatures, where single particles are able to surmount energetic barriers and contribute to particle transport, the solitons lead to strong variations of particle currents with particle size and driving force. The theoretically predicted soliton occurrence was verified in a collaboration with Prof. Tierno’s experimental group at the University of Barcelona. In the experiments conducted by this group, polystyrene particles in aqueous solution were confined to move along a narrow circular channel with a periodic potential inside the channel. For particle sizes close to the magic ones, soliton formation requires no thermal activation. Thermal generation of solitons with finite lifetime is also possible. Such thermally activated solitons can act as defects in highly jammed particle configurations, allowing for measurable particle currents in such states. We derived generation rates for the thermally activated solitons and set up a scaling theory, which describes the dependencies of defect-mediated particle currents on particle and system size. Another key result of the project is that potential barriers become effectively enhanced in flow-driven systems due to hydrodynamic interactions. These interactions describe forces mediated by solvent flows. The enhancement is in contrast to an effective barrier reduction by hydrodynamic interactions in force-driven systems reported earlier in the literature. We explained the effective barrier enhancement and the difference between flow- and force-driven systems by an analysis of mobility tensors accounting for hydrodynamic interactions. Due to the effective barrier enhancement, particle transport slows down. The slowing down was observed in experiments performed by the Barcelona group and could be successfully modeled in the project by computer simulations. Further achievements are developments of theories for single-file transport when particles can partially penetrate each other, for single-file diffusion of hard spheres with adhesive interactions described by an attractive contact interaction, and for single-file dynamics of hard-sphere mixtures. To tackle cooperative particle movements due to propagation, merging and fragmentation of particle clusters in computer simulations, we designed a Brownian cluster dynamics method and an algorithmic implementation of this method.

Publications

• Driven transport of soft Brownian particles through pore-like structures: Effective size method. The Journal of Chemical Physics, 155(18).
  Antonov, Alexander P.; Ryabov, Artem & Maass, Philipp
  
• Hydrodynamic Interactions Can Induce Jamming in Flow-Driven Systems. Physical Review Letters, 127(21).
  Cereceda-López, Eric; Lips, Dominik; Ortiz-Ambriz, Antonio; Ryabov, Artem; Maass, Philipp & Tierno, Pietro
  
• Brownian dynamics simulations of hard rods in external fields and with contact interactions. Physical Review E, 106(5).
  Antonov, Alexander P.; Schweers, Sören; Ryabov, Artem & Maass, Philipp
  
• Collective excitations in jammed states: ultrafast defect propagation and finite-size scaling. New Journal of Physics, 24(9), 093020.
  Antonov, Alexander P.; Voráč, David; Ryabov, Artem & Maass, Philipp
  
• Solitons in Overdamped Brownian Dynamics. Physical Review Letters, 129(8).
  Antonov, Alexander P.; Ryabov, Artem & Maass, Philipp
  
• Brownian particle transport in periodic structures”, PhD thesis (Osnabruck University, Germany, Aug. 2023)
  A. P. Antonov
  
• Overcrowding induces fast colloidal solitons in a slowly rotating potential landscape. Nature Communications, 14(1).
  Cereceda-López, Eric; Antonov, Alexander P.; Ryabov, Artem; Maass, Philipp & Tierno, Pietro
  
• Scaling laws for single-file diffusion of adhesive particles. Physical Review E, 107(4).
  Schweers, Sören; Antonov, Alexander P.; Ryabov, Artem & Maass, Philipp
  
• Single-file transport of binary hard-sphere mixtures through periodic potentials. The Journal of Chemical Physics, 159(11).
  Voráč, David; Maass, Philipp & Ryabov, Artem