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BP: Fachverband Biologische Physik

BP 16: Poster Session I

BP 16.58: Poster

Tuesday, March 27, 2007, 17:00–19:30, Poster D

Floppy modes: low-energy elastic excitations of stiff polymer networks — Claus Heussinger, •Boris Schaefer, and Erwin Frey — Arnold Sommerfeld Center for Theoretical Physics, LMU Muenchen, Theresienstrasse 37, 80333 Muenchen

Stiff polymers, unlike their flexible counterparts, have a highly anisotropic elastic response, where the low-energy elastic excitations are of bending nature, while stretching deformations are energetically highly unfavourable. Based on this scale separation between bending and stretching mode we analyze the elasticity of networks of stiff polymers in terms of the "floppy-mode" concept. A floppy mode defines a deformation field that is constructed by requiring polymer end-to-end distances to stay constant during the course of deformation. As a consequence, stretching deformations are avoided and network elasticity is exclusively due to the bending mode. Singular value decomposition of the kinematic matrix is used to construct the orthonormalized set of floppy modes, which may be viewed as the direct analog to the set of vibrational eigenmodes in networks of central force springs.