The Rouse model describes the conformational dynamics of an ideal chain.
In this model, the single chain diffusion is represented by Brownian motion of beads connected by harmonic springs.
[2] An important extension to include hydrodynamic interactions mediated by the solvent between different parts of the chain was worked out by Bruno Zimm in 1956.
[2] In a polymer melt, the Rouse model correctly predicts long-time diffusion only for chains shorter than the entanglement length.
For long chains with noticeable entanglement, the Rouse model holds only up to a crossover time τe.