Theory of melting, based on statistics of the rotational group elements

Mean field theory of melting based on statistics of the rotational group elements is considered for 2D and 3D systems. According to the theory, melting is orientational order – disorder phase transition. With two dimensions, it is the second order transition, while with three dimensions it is the first order one, and liquid is (meta) stable down to zero temperature. The theory contains only one phenomenological parameter