THREE-DIMENSIONAL GONIHEDRIC SPIN SYSTEM

We perform Monte–Carlo simulations of a three-dimensional spin system with a Hamiltonian which contains only four-spin interaction term. This system describes random surfaces with extrinsic curvature – gonihedric action. We study the anisotropic model when the coupling constants β_S for the space-like plaquettes and β_T for the transverse-like plaquettes are different. In the two limits β_S = 0 and β_T = 0 the system has been solved exactly and the main interest is to see what happens when we move away from these points towards the isotropic point, where we recover the original model. We find that the phase transition is of first order for β_T = β_S ≈ 0.25, while away from this point it becomes weaker and eventually turns to a crossover. The conclusion which can be drawn from this result is that the exact solution at the point β_S = 0 in terms of 2D-Ising model should be considered as a good zero-order approximation in the description of the system also at the isotropic point β_S = β_T and clearly confirms the earlier findings that at the isotropic point the original model shows a first-order phase transition.