C60固体中的相变

本文用（ｅｘｐ－６－１）势对固体Ｃ６０中分子间的相互作用进行计算，给出常温以下固体Ｃ６０中分子存在的状态，计算表明，常温下Ｃ６０高速旋转，随着温度降低，旋转速度逐渐减小，并且旋转轴向也逐渐趋于单一，当降到－２６０Ｋ时发生一级相变，此时ＦＣＣ晶胞中（０，０，０），１／２，１／２，０），（１，１／２，１／２）及（１／２，０，１／２）四套格点上的分子各只绕［１１１］三重轴旋转，Ｃ６０晶体从ＦＣＣ结构变为

Phase Transition in Solid C_(60)

The interactions between C60 molecules in solid state are calculated by the potential model (exp-6-1). The states of C6o molecules in solid are given at room temperature and at lower temperature. C60 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-temperatuxe FCC phase to the ordered SC structure. The molecule equlvalence 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 [111], that at (0,1/2,1/2) around [111] and at (1/2,0,1/2) around [111]. At about 90K, the system undergoes a second-order phase transtion-glass transition.