The Structure And The Character Study Of The C₂₀ Isomers

First, the basic structures character of the three C₂₀ isomers are studied, then the stability sequence of the three ones have been compared by the HMO method. On the basis of knowing the character of the fullerene C₂₀, the DFT theory which is suitable for the fullerene computation have been chosen to complete all the calculation. The B3LYP level and the 6-31G* basic group have been chosen when considering the real condition. The Conduction Characteristics of the C₂₀ with I h symmetry have been studied. The total energy, the energy gap, the vibration spectrum and the electronic structure character of the C₂₀ molecule with C₁ symmetry are all studied, the result suggests a pronounced degree of electron delocalization which perhaps indicates the reason of the stability of C₂₀ molecule disobeying the IPR rule. The total five possible dodecahedral structures which were computed to be the lowest-energy candidates of C₂₀ have been studied. The geometric optimization, the vibration spectrum and NBO have been computed. Those are also the innovation of the article. The results suggested that: the shortest C-C length is 0.1368nm and the longest one is 0.1538nm which all belong to the C 2 symmetry. The bond length implys the electronic delocalization which can also be seen from the DOS figures. The energies of the isomers have small difference, so do the LUMO-HOMO energy gaps of the isomers. The energies of C₂₀ does not reduce following the symmetry's deduce. The sequence of the stability is: C₂> D_2h>D_3d>C_i>C_2h. The infrared spectrums of the five isomers are almost the same that they have almost the same number and the same intensity of the character peak value. The NBO computations suggest that the C₂₀ fullerene molecules with all those symmetry have almost the same electronic transfer characters. So theoretically speaking, the vibration spectrum and NBO results can all be the reference to differentiate the isomers. The ¹³CNMR spectrum is a strong tool to definate the isomers.