Díaz-Tendero Sergio, Alcamí Manuel, Martín Fernando
Departamento de Química, C-9, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
J Chem Phys. 2005 Nov 8;123(18):184306. doi: 10.1063/1.2104467.
We present a theoretical study of the structure and electronic properties of positively charged C60(q+) and C58(q+) fullerenes (q = 0-14). Electronic energies and optimum geometries have been obtained using density-functional theory with the B3LYP functional for exchange and correlation. We have found that closed- and semiclosed-shell C60(q+) ions (q = 0, 5, and 10) preserve the original icosahedral symmetry of neutral C60. For other charges, significant distortions have been obtained. The C58(q+) fullerenes are, in general, less symmetric, being C58(8+) the closest to the spherical shape. Most C60(q+) fullerenes follow Hund's rule for spin multiplicity, while most C58(q+) fullerenes are more stable with the lowest spin multiplicity. The calculated ionization potentials for both kinds of fullerenes increase almost linearly with charge, except in the vicinity of C60(10+) and C58(8+). We have also explored the region of the potential-energy surface of C60(q+) that leads to asymmetric fission. Minima and transition states corresponding to the last steps of the fission process have been obtained. This has led us to conclude that, for 3 < or = q < or = 8, C2(+) emission is the preferred fragmentation channel, whereas, for higher q values, emission of two charged atomic fragments is more favorable. The corresponding fission barrier vanishes for q > 14.
我们对带正电的C60(q+)和C58(q+)富勒烯（q = 0 - 14）的结构和电子性质进行了理论研究。使用密度泛函理论结合B3LYP泛函进行交换和关联，得到了电子能量和最佳几何结构。我们发现，闭壳层和半闭壳层的C60(q+)离子（q = 0、5和10）保留了中性C60原有的二十面体对称性。对于其他电荷，出现了显著的畸变。一般来说，C58(q+)富勒烯的对称性较低，其中C58(8+)最接近球形。大多数C60(q+)富勒烯遵循洪德自旋多重性规则，而大多数C58(q+)富勒烯在最低自旋多重性时更稳定。两种富勒烯的计算电离势几乎随电荷呈线性增加，但在C60(10+)和C58(8+)附近除外。我们还探索了C60(q+)势能面中导致不对称裂变的区域。得到了裂变过程最后几步对应的极小值和过渡态。由此我们得出结论，对于3≤q≤8，C2(+)发射是首选的碎片化通道，而对于更高的q值，发射两个带电原子碎片更有利。当q > 14时，相应的裂变势垒消失。
