Collapse transition of a square-lattice polymer with next nearest-neighbor interaction

TL;DR

This paper investigates the collapse transition of a square-lattice polymer considering both nearest and next-nearest neighbor interactions, revealing a more pronounced transition and universality with the classic theta point.

Contribution

It provides the first exact calculation of partition function zeros for this model, estimating critical parameters and confirming universality class.

Findings

Transition is more pronounced with next-nearest interactions.

Crossover exponent and transition temperature are estimated.

Model belongs to the same universality class as the classic theta point.

Abstract

We study the collapse transition of a polymer on a square lattice with both nearest-neighbor and next nearest-neighbor interactions, by calculating the exact partition function zeros up to chain length 36. The transition behavior is much more pronounced than that of the model with nearest-neighbor interactions only. The crossover exponent and the transition temperature are estimated from the scaling behavior of the first zeros with increasing chain length. The results suggest that the model is of the same universality class as the usual theta point described by the model with only nearest-neighbor interaction.