Roughening and preroughening in the six vertex model with an extended range of interaction

TL;DR

This paper investigates the phase diagram of an extended-range BCSOS model related to crystal surfaces, revealing complex phase transitions and non-Ising critical behavior, with implications for understanding surface reconstruction phenomena.

Contribution

It introduces a detailed analysis of the BCSOS model with extended interactions, identifying a reconstructed phase, disordered flat phase, and complex transition behaviors including Kosterlitz-Thouless and non-Ising exponents.

Findings

Identification of a 2x2 reconstructed phase.

Discovery of a disordered flat phase.

Observation of non-Ising critical exponents.

Abstract

We study the phase diagram of the BCSOS model with an extended interaction range using transfer matrix techniques, pertaining to the (100) surface of single component fcc and bcc crystals. The model shows a 2x2 reconstructed phase and a disordered flat phase. The deconstruction transition between these phases merges with a Kosterlitz-Thouless line, showing an interplay of Ising and Gaussian degrees of freedom. As in studies of the fully frustrated XY model, exponents deviating from Ising are found. We conjecture that tri-critical Ising behavior may be a possible explanation for the non-Ising exponents found in those models.