C_(56)X_(10)(X=F,Cl,Br,I)的结构稳定性和电子性质

Structure Stability and Electronic Properties of C_(56)X_(10)(X=F,Cl,Br,I)

采用密度泛函理论(DFT)中的广义梯度近似(GGA)方法对C56X10(X=F,Cl,Br,I)的结构稳定性和电子性质进行了计算研究.结构稳定性计算表明:对于C56X10(X=F,Cl,Br,I),能隙、反应热、最大振动频率和最小振动频率都随着X原子序数的增加而减小,表明C56X10(X=F,Cl,Br,I)的稳定性随着X原子序数的增加而逐渐降低,其中C56F10最为稳定.前人在实验上已成功合成出C56Cl10,因此,我们推测C56F10有望在实验上成功合成.前线轨道计算发现,C56相邻的五边形公共顶点以及两个六边形-五边形-六边形公共顶点是笼子中化学活性最强的部位,有利于卤族元素的外部吸附.此外,计算结果还显示,C56X10(X=F,Cl,Br,I)的电负性随着X原子序数的增大而逐渐减弱,C—X基团的电负性因位置的不同而不同.

The generalized gradient approximation （GGA） method based on density functional theory （DFT） was used to analyze the structural stability and electronic properties of the unconventional carbon halogen fullerenes C56X10（X=F, Cl, Br, I）. The investigation of structural stability indicates that the evolution of energy gaps, the reactive heat （AE）, the maximal vibration frequencies, and the minimal vibration frequencies of C56X10（X=F, Cl, Br, I） all decrease with an increase in the atomic number of X. This indicates that the stabilities should decrease from C56F10 to Cu56I10C56F10 is the most stable molecule among the four molecules and we oredict that it can be isolated and svnthesized because of the successful isolation of C56Cl10. From the analysis of the frontier orbitals of C56 and C56X10（X=F, Cl, Br, I）, the C atoms are located at the abutting pentagon sites and both the hexagon-hexagon-pentagon vertex functions are the most active sites on C56 and this is suitable for halogen atom attachment. Our calculations also show that the electronegativity of C56X10（X=F, Cl, Br, I） cluster molecules decrease with an increase in the atomic number of X. However, the electronegativity of the C--X fragment in the molecules is affected by its location.