STEP-STEP INTERACTIONS AND CORRELATIONS FROM 1D HARD-CORE BOSON MAPPING

The theory of the preroughening transition of an unreconstructed surfa ce, and the ensuing disordered hat (DOF) phase, is formulated in terms of steps. Finite terraces play a crucial role in the formulation. We start by mapping the statistical mechanics of interacting (up and down ) steps onto the quantum mechanics of two species of one-dimensional h ard-core bosons. The finite terraces are generated by a number-non-con serving term in the boson Hamiltonian, which forbids a mapping in term s of fermions.. Once the boson problem is solved, we find the DOF phas e is stabilized by short-range repulsions of like steps. On-site repul sion of up-down steps is essential in producing a DOF phase, whereas a n off-site attraction between them is favorable but not required. Step -step correlations and terrace width distributions can be directly cal culated with this method. (C) 1998 Elsevier Science B.V. All rights re served.