Phase Transition in Solid Co-3

The. interactions between C,v, molecules in solid state are calculated by the pot cola] model)del (ex-p 6 1). The states of C-60, molecules in solid are given at room temperature and at lower temperature C-60 molecule rotates rapidly at room temperature: the rotation rate decreases and the rotational axes tend to ordering as temperature becomes lower. And at about 260K the structure undergoes a first-order phase transiton from the high-temperature FCC phase to the ordered SC structure. The molecule equivalence above 260K is now broken by rotating the four molecules through the same angle but around different < 111 > axes: the molecule at (0,0,0) around [111, that at (1/2,1/2,0) around [1 (11) over bar], that at (0,1/2,1/2) around 111] and at (1/2,0,1/2) around [(11) over bar1]. At about 90K the system undergoes a second order phase tranistion glass transition.