We present a conceptual and computational framework for chemically ordered Pb(Mg 1/3 Nb 2/3 O 3) (PMN) type supercells violating disorder of the host lattice. The effective Hamiltonian is specified by invariance under permutations of supercells and by the dipole-dipole interaction supporting both local nonzero and zero mean polarization of the structure. Statistics treated in canonical ensemble within the mean field approach reveals emergence of polar nanoregions as supported by interplay between the (random) initial state polarization of supercells and their interactions increased at cooling.
Integrated Ferroelectrics, 2011, vol. 123, p. 32-39.