2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/107080We report large scale Monte Carlo simulations of the equilibrium discrete Laplacian roughening (dLr) model, originally introduced as the simplest one accommodating the hexatic phase in two-dimensional melting. The dLr model is also relevant to surface roughening in molecular beam epitaxy (MBE). Our data suggest a single phase transition, possibly of the Kosterlitz-Thouless type, between a flat low-temperature phase and a rough, tensionless, high-temperature phase. Thus, earlier conclusions on the order of the phase transition and on the existence of a hexatic phase are seen as due to finite size effects, the phase diagram of the dLr model being similar to that of a continuum analog previously formulated in the context of surface growth by MBE.4 pages, 4 figures. Accepted as a Rapid Communication in Phys. Rev. EStatistical MechanicsSoft Condensed Mattertext