Computational investigations of inhomogeneous elastic effects near phase transitions

We present different approaches to computer simulations of the order-disord er phase transition in thiocyanate crystals. In these systems the order par ameter is coupled to the strain by coupling of the type eta(2)epsilon. This coupling plays the dominant role in the behavior of the system below T-c. Molecular Dynamics and Monte Carlo techniques give the proper temperature d ependence of the order parameter and the behavior of the fluctuations simil iar to that observed experimentally. The ab initio calculations allow us to render properly the structural properties of crystals like KSCN and additi onally can become the basis for more realistic phenomenological models.