Chen De-Li, Tian Wei Quan, Feng Ji-Kang, Sun Chia-Chung
State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.
J Chem Phys. 2008 Jan 28;128(4):044318. doi: 10.1063/1.2821022.
All the 924 classical isomers of fullerene C(56) have been investigated by PM3, and some most stable isomers are refined with HCTH/3-21G and B3LYP6-31G(d) methods. D(2):003 with the least number of adjacent pentagons is predicted to be the most stable isomer at B3LYP/6-31G(d) level, while C(s):022 and C(2):049 possess nearly degenerate energies with relative energies of 0.03 and 3.90 kcal/mol, respectively. However, as to dianionic C(56)(2-) fullerene, C(2v):011 is predicted to be the most stable isomer. Investigations also show that the encapsulation of Ca atom in C(56) fullerene is exothermic and the metallofullerenes Ca@C(56) can be described as Ca(2+)@C(56)(2-). The computed relative stabilities show that the D(2):003 behaves more thermodynamically stable than other isomers in a wide temperature interval, and C(2v):011 should also be an important component. The electronic isomerization of C(56) (C(2v):011) and C(50) (D(5h):002) indicates that this phenomenon might be rather general in fullerenes and causes different properties, thus bringing about new possible applications of fullerenes. The static second-order hyperpolarizabilities of the three most stable isomers are slightly larger than that of C(60).
通过PM3方法研究了富勒烯C(56)的所有924种经典异构体,并使用HCTH/3 - 21G和B3LYP6 - 31G(d)方法对一些最稳定的异构体进行了优化。预测在B3LYP/6 - 31G(d)水平下,相邻五边形数量最少的D(2):003是最稳定的异构体,而C(s):022和C(2):049具有几乎简并的能量,相对能量分别为0.03和3.90千卡/摩尔。然而,对于双阴离子C(56)(2 -)富勒烯,预测C(2v):011是最稳定的异构体。研究还表明,Ca原子封装在C(56)富勒烯中是放热的,金属富勒烯Ca@C(56)可描述为Ca(2 +)@C(56)(2 -)。计算得到的相对稳定性表明,在较宽的温度区间内,D(2):003比其他异构体在热力学上更稳定,C(2v):011也应该是一个重要的组分。C(56)(C(2v):011)和C(50)(D(5h):002)的电子异构化表明这种现象在富勒烯中可能相当普遍,并导致不同的性质,从而带来富勒烯新的可能应用。三种最稳定异构体的静态二阶超极化率略大于C(60)的静态二阶超极化率。