Two-dimensional lattice liquids

Evidence is presented, based on transfer-matrix and Monte Carlo calculation s, for the occurrence of a gas-liquid phase transition in suitably construc ted, two-dimensional lattice-gas models with extended hard-core repulsion o n the triangular lattice. Three different models having this property are i dentified. The first system is characterized by nearest-neighbor exclusion and an interparticle attraction ranging from second- to fourth-neighbor dis tance. In a further example, the hard core reaches second neighbors, while the attraction ranges from third to fifth neighbors. Finally, in a third mo del, the core extends up to fourth neighbors, while the attraction covers a ll distances from fifth to eighth neighbors. I discuss how to use these res ults in order to make a realistic lattice simulation of the triangular, (11 1) surface of a fee solid.