Orientational Ordering in Anisotropic Fullerides

Abstract

A microscopic description of structural and orientational ordering of the high-symmetry anisotropic fullerides (AF) condensed state is presented. It is shown that the formed translational ordering removes degeneracy in the direction of preferred molecular orientation axis and leads to the appearance of the cross terms in pseudopotential inducing orientational ordering. Numerical calculations of the order parameters were carried out and phase transition temperature dependencies from molecular parameters were obtained. Using model parameters corresponding to C₇₀ molecule the estimation of the structure phase transition temperature was obtained T_PC-1 ≊ 50K.