摘要
采用C60 分子之间相互作用势的Kihara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 [10 0 ]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 2 98K时的等压热容 ,所得数值与实验值相符 .
The simplest intermolecular potential for C-60 is Lennard-Jones 6-12 type potential, but the L-J potential-couldn't consider the volume of C-60 molecules, so the potential is not correct in most cases. Kihara type interaction potential between two C-60 molecules has been proposed recently. This intermolecular potential for C-60 includes the volume of C-60 molecules, so it is better than L-J potential. According to the Kihara type interaction potential for C-60 molecules, lattice vibrations of fcc C-60 crystal have been studied. Distribution of phonon dispersion frequencies of fcc C-60 crystal along [111], [110] and [100] directions has been obtained. Distribution of state-density of fcc C-60 crystal has been gained too. The Debye temperature Theta(D) of fcc C-60 crystal has been calculated, because the fcc C-60 crystal is molecular crystal and the Theta(D) is 75.5 K lower than that of common metal crystals. According to the distribution of state-density of fcc C-60 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.
基金
山东省自然科学基金资助课题 (Y2 0 0 0B0 5 )
