Orientational transitions in a one-dimensional lattice of molecules with dipole and quadrupole moments

Abstract

The phase diagram of a linear lattice of point molecules, with dipole and quadrupole moments, is obtained in the mean-field approximation. A wide variety of different phases is observed, especially in a narrow range of values of the ratio between the dipole and quadrupole moments ( p/ Q). Two interesting features are studied with care: the existence of a double well in the potential seen by the molecules, which is created by the molecules themselves, and the fact that a sublattice of molecules gets increasingly ordered as the temperature increases, in a certain region of the p/ Q. T phase diagram.