2004/12/18 by Supurna Sinha, Joseph Samuel · 1 citation
Biochemistry, Genetics and Molecular Biology · Materials Science · Physics and Astronomy · #Force Microscopy Techniques and Applications #Material Dynamics and Properties #Theoretical and Computational Physics #cond-mat.soft #cond-mat.stat-mech #q-bio.BM
paper · pdf · doi:10.1103/physreve.71.021104
to appear in Physical Review E
arxiv created 2004/12/18 · openalex publication_date 2005/02/24 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
We study the role of fluctuations in single molecule experimental measurements of force-extension (f-zeta) curves. We use the worm-like chain (WLC) model to bring out the connection between the Helmholtz ensemble characterized by the free energy [F(zeta)] and the Gibbs ensemble characterized by the free energy [G(f)] . We consider the rigid rod limit of the WLC model as an instructive special case to bring out the issue of ensemble inequivalence. We point out the need for taking into account the free energy of transition when one goes from one ensemble to another. We also comment on the "phase transition" noticed in an isometric setup for semiflexible polymers and propose a realization of its thermodynamic limit. We present general arguments which rule out nonmonotonic force-extension curves in some ensembles and note that these do not apply to the isometric ensemble.