Elastic dumbell

Hence, 90% of the total mean squared end-to-end distance of a chain originates from the lowest order Rouse-modes. In theorical treatments, polymer chains are sometimes substituted by elastic dumbells, set up by two beads connected by a spring. The justification for this simplification follows from the dominant role of the primary Rouse-modes. 

Finite-extensibility non-linear elastic (FENE) extension of dumbell model Multimode Zimm model... 

For a FENE-type model with nonlinear elastic force of the dumbell, the restituting elastic force of a molecule can be represented in the form F = —where fo is th characteristic spring restitution coefficient per unit mass and Fq = L / L — trA) with L the maximum length of the polymer. The evolution equation for the elastic contribution is given in terms of the deformation or conformational tensor A = (RR), which is now related to the elastic part of the stress tensor by the formula The equation is... 

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