Effects of ground state disorder without frustration: Liquid crystals with interactions favoring orthogonal ordering

We investigate the effect of nonzero ground state disorder which does not involve any frustration or competition, by studying a nematic liquid crystal-type model with an interaction which favors orthogonal orientations of nearest-neighbor rods. From Monte Carlo simulations, we find a phase transition with long-range ordering for d = 3, so that the ground state disorder does not increase the minimum integral dimensionality where the model has a (finite-temperature, symmetry-breaking) phase transition. The nature of the long-range order is discussed. The transition is found to be continuous, in agreement with a theoretical argument. For comparison, the d = 4 and d = 2 versions of the model are also briefly studied.