Eur. Phys. J. B 6, 63-73 (1998)
https://doi.org/10.1007/s100510050527

Swollen-collapsed transition in random hetero-polymers

International School for Advanced Studies (SISSA), and Istituto Nazionale di Fisica della Materia, Via Beirut 2-4, 34014 Trieste, Italy and Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34100 Trieste, Italy

Corresponding author: ^a trovato@shannon.sissa.it

Received: 10 April 1998
Revised: 4 June 1998
Accepted: 1 July 1998
Published online: 15 November 1998

Abstract

A lattice model of a hetero-polymer with random hydrophilic-hydrophobic charges interacting with the solvent is introduced, whose continuum counterpart has been proposed by Garel, Leibler and Orland [CITE]. The transfer matrix technique is used to study various constrained annealed systems which approximate at various degrees of accuracy the original quenched model. For highly hydrophobic chains an ordinary θ-point transition is found from a high temperature swollen phase to a low temperature compact phase. Depending on the type of constrained averages, at very low temperatures a swollen phase or a coexistence between compact and swollen phases are found. The results are carefully compared with the corresponding ones obtained in the continuum limit, and various improvements in the original calculations are discussed.