Transfer-matrix study of the staggered body-centered solid-on-solid model

The phase diagram of the staggered six vertex, or body-centered solid-on-solid model, is investigated by transfer-matrix and finite-size scaling techniques. The phase diagram contains a critical region, bounded by a Kosterlitz-Thouless line, and a second-order line describing a deconstruction transition. In part of the phase diagram the deconstruction line and the Kosterlitz-Thouless line approach each other without merging, while the deconstruction changes its critical behavior from Ising-like to a different universality class. Our model has the same type of symmetries as some other two-dimensional models, such as the fully frustrated XY model, and may be important for understanding their phase behavior. The thermal behavior for weak staggering is intricate. It may be relevant for the description of surfaces of ionic crystals of CsCl structure.