In this paper we consider the model of a flexible polymer chain embedded in a quenched random medium with long-range disorder correlations. Using the Feynman path integral approach we show that for the case of long-range quadratic correlations, we obtain an analytical result. The result is [Formula: see text], where 〈R2〉 is the mean square end-to-end distance of the polymer chain, ξ is the correlation length of disorder, Δ is an unknown parameter, b is the Kuhn step length, ρ is the density of random obstacles and N is the number of links. It is shown that for a polymer chain in a random media with long-range quadratic correlations, where ρ is not too high, the behavior of the polymer chain is like that of a free chain. This result agrees with the calculation using the replica method. However, in a medium where ρ is very high, the variation of the mean square end-to-end distance with disorder and its distance depending on ρ are found in our approach.
Characterizing magnetic resonance signal decay due to gaussian diffusion: The path integral approach and a convenient computational method