立方面心C60晶体晶格振动的研究

采用C60分子之间相互作用势的Kihra形式,研究了立方面心C60晶体的晶格振动问题,得到了质心振动沿111]、110]及100]方向的声子散射圆频率分布曲线及C60晶格振动频率的态密度分布.采用所得到的C60晶格振动频率的态密度分布,计算了晶体C60在298 K时的等压热容,所得数值与实验值相符.

Studies on the Lattice Vibrations of fcc C60 Crystal

The simplest intermolecular potential for C60 is Lennard-Jones 6-12 type potential, but the L-J potential couldn’t consider the volume of C60 molecules, so the potential is not correct in most cases. Kihara type interaction potential between two C60 molecules has been proposed recently. This intermolecular potential for C60 includes the volume of C60 molecules, so it is better than L-J potential. According to the Kihara type interaction potential for C60 molecules, lattice vibrations of fcc C60 crystal have been studied. Distribution of phonon dispersion frequencies of fcc C60 crystal along 111, 110 and 100 directions has been obtained. Distribution of state-density of fcc C60 crystal has been gained too. The Debye temperature ΘD of fcc C60crystal has been calculated, because the fcc C60 crystal is molecular crystal and the ΘD is 75.5 K lower than that of common metal crystals. According to the distribution of state-density of fcc C60 crystal, heat capacity at 298 K and 101 kPa has been obtained here, its value is 526.23 J/Kmol and the result accords with the experimental value.