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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Modeling and Simulation of Soft Matter I
CPP 17.5: Vortrag
Dienstag, 18. März 2025, 10:45–11:00, H38
Reducing dynamical helical polymers to 1D Ising models: long-range effects from polymer self-avoidance — •Keerti Chauhan1, Marcus Müller2, and Kostas Daoulas1 — 1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany — 2Georg-August-Universität Göttingen, Institute for Theoretical Physics, 37077 Göttingen, Germany
Cooperative chiral order in dynamic helical polymers (DHP) is commonly understood by reducing them to 1D Ising chains. Each spin can switch between σ= −1 and σ = +1 to represent rapid interconvertion between left-handed (M) and right-handed (P) helical twist. Spins are ferromagnetically coupled to capture the energetic disadvantage of boundaries between P and M domains. Currently, all 1D Ising models of DHP assume nearest-neighbor (NN) spin-spin interactions. We use a minimal model to challenge this assumption and investigate whether polymer self-avoidance, due to excluded volume, leads to effective non-local coupling between spins. Polymers are represented by freely-jointed chains with reversible hinges and helicity is described by a NN 1D Ising Hamiltonian with coupling strength J. Ideal and self-avoiding DHP are generated via a Monte Carlo scheme. First, we verify that in ideal chains the spins reproduce the statistics of a NN 1D Ising model with coupling strength J. Next, we find that chain self-avoidance does create effective long-range interactions between spins, as demonstrated by spin-spin correlation functions and free-energy calculations. These interactions renormalize J and create finite-size effects that are inconsistent with a NN 1D Ising behavior.
Keywords: helical polymer; chirality; Ising model; modeling; polymer theory