Folding transitions of the triangular lattice with defects

TL;DR

This paper generalizes a model of triangular lattice folding to include defects, analyzes its phase diagram using the cluster variation method, and explores the transition from pure Ising to folding behavior, revealing complex multicritical points.

Contribution

It introduces a generalized folding model with defects on the triangular lattice and analyzes its phase diagram, extending previous studies with new insights into multicritical behavior.

Findings

Phase diagram determined in the hexagon approximation.

Crossover from Ising to folding model studied.

Rich structure with multiple multicritical points identified.

Abstract

A recently introduced model describing the folding of the triangular lattice is generalized allowing for defects in the lattice and written as an Ising model with nearest-neighbor and plaquette interactions on the honeycomb lattice. Its phase diagram is determined in the hexagon approximation of the cluster variation method and the crossover from the pure Ising to the pure folding model is investigated, obtaining a quite rich structure with several multicritical points. Our results are in very good agreement with the available exact ones and extend a previous transfer matrix study.