Entropy of phase-separated structures

The morphology of phase-separated structures can often be accurately modelled by level-cut Gaussian random fields. We consider the statistical ensemble of level-cut states and its relation to the Ising model with a long-range interaction. The entropy of the ensemble can be numerically calculated using the local cluster method. The method is tested on the exact solution of one-dimensional Ising model with the long-range Kac potential and illustrated using examples of level-cut Gaussian fields. At least in one-dimensional systems, the cluster method is easy to apply and produces accurate results.