| The geometric structures and the electronic properties of C60(CF3)n(n=2, 4, 6, 10) are studied using the generalized gradient approximation (GGA) based on the density functional theory (DFT). As we know, in the course of forming C60(CF3)n(n=2, 4, 6, 10), there are two addition types for CF3 groups. One is that the CF3 groups are either meta or para to one anther on a ribbon of edge-sharing Ce(CF3)2 hexagons(each pair of adjacent hexagons shares a common CF3 group), the other is that all CF3 groups are on contiguous cage carbon atoms, a series of 1, 2 additions, with more than two CF3 groups on some hexagons and pentagons. We have deeply researched into them by analyzing the properties for each of C60(CF3)n(n=2, 4, 6, 10). For C60(CF3)4, there are three isomers, C60(CF3)4-1, C60(CF3)4-2, and C60(CF3)4-3, which belong to p-p-p, p-m-p, and contiguous addition types respectively. The stabilization of them is in the order C60(CF3)4-1 > C60(CF3)4-2 > C60(CF3)4-3. For C60(CF3)6, there are three isomers, ie. C60(CF3)6-1, C60(CF3)6-2, and C60(CF3)6-3. They belong to the p-p-p-m-p, p-m-p-m-p, and contiguous addition type respectively. The stabilization order of them is C60(CF3)6-1 > C60(CF3)6-3 > C60(CF3)6-2. The most important conclusion for C60(CF3)n(n=2, 4, 6, 10) is that: (1) the more the additive CF3 groups are, the larger the Eg will be. Thus, C60(CF3)10 has the largest Eg of 1.678eV. That is to say, the system after bonding to ten CF3 groups will become more stable than C6o- (2)By analyzing the energy level and the density of states of these systems, we find that the contributions from CF3 groups to both HOMO and LUMO are very small, while the largest one is of only 10 percentages. So the electron attachment and detachment both mainly occur on the carbon cages not on the CF3 groups. (3) The hybridized energy levels coming from CF3 mainly distributed between the energy range from -10eV to -4eV, and they have no influence on the Ef. Finally, we focused on the analysis of the Mulliken charge and the net spin populations. The different CF3 was discovered with different charges, however, the average electron attachment for CF3 groups are almost same only with small increasement along with the adding of CF3 groups. |
PDF Full Text Request