ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
A matrix approach is adopted to evaluate the partition function of random-walk chains between parallel walls. Assuming an attractive potential ε at the sites contiguous to the walls, a second-order transition is deduced at the temperature T* that makes ε/T equal to the entropy loss of the chain bonds reaching those sites. At T=T*, the walls act as reflecting barriers to the chain, whereas at T≥T* and at T≤T*, they change to repelling and attracting barriers, respectively. In the limit of an infinitely long chain comprised between infinitely distant walls, T* takes the role of a tricritical temperature, as we have three distinct states at T≥T* (the chain is repelled from the walls), at T=T* (the chain density is uniformly distributed between the walls), and at T≤T* (the chain collapses on either wall). Denoting as r the ratio between the probability of an end atom and that of a middle-chain atom touching the walls, we obtain r(very-much-greater-than)1, r=6/5, and r≤1 at T≥T*, T=T*, and T≤T*, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.464730
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