分子C_nX_4(n=28,40;X=H,F,Cl)的振动光谱的密度泛函理论研究(英文)

The computational vibrational spectrum of C_nX_4(n=28,40;X=H,F,Cl) with density function theory

本文中,首先证明了C_nX_4(n=28,40;X=H,F,Cl)分子最稳定的结构具有T_d对称性。利用密度泛函理论研究了C_nX_4的振动光谱。从频率分析中我们得到当修饰性的原子位于T_d对称性的C_(28)X_4和C_(40)X_4的势能面上的4个顶点时,分子的能量具有最低值。我们还将C_nH_4(n=28,40;X=H,F,Cl)和CX_4的振动光谱进行对比,得出笼的骨架振动。频率分析中具有最大波数的频率对应分子的笼骨架振动,所以对于C_(28)X_4(X=H,F,Cl)或C_(40)X_4(X=H,F,Cl)来说,修饰原子的改变对这个频率值基本上没有影响,但是碳笼骨架上碳原子数的改变对这个频率的影响非常大。

Herein, we demonstrate that the most stable structures of the C,X4 （n=28, 40 and X=H, F, Cl） molecule are of Td symmetry. The vibrational spectrum of the CnX4 have been studied by using the Density Function Theory. From the vibration frequency analysis the authors prove when the modifying atoms are located at the four tops of C28X4 and C40X4 potential surface with Td symmetry structure, the molecule energy is of the lowest value. By the comparison of vibration spectrum of CnX4 （n=28, 40; X=H, F, Cl） with those of CX4 ,the authors obtained the skeleton vibration. The maximal frequency corresponds to the molecule＇s skeleton vibration, so the change of the modifying atoms has basically little effect on this frequency as regard to C28X4 （X=H, F, Cl） or C40X4 （X=H, F, Cl）, but the change of the numbers of carbon atoms on the carbon skeleton has very great effect on this frequency.