M @ C <sub> 20 </ Sub> F <sub> 20 </ Sub> (m = Li, Na And Be And Mg) And H <sub> 20 </ Sub> @ C, <sub> 80 </ Sub> X <sub> 60 </ Sub> (x = H, F) The Geometric Structure And Electronic Properties O

Since the discovery and bulk preparation of C₆₀, the unique properties of fullerenes have been attracted attention of an increasing number of scientists. The research of the fullerene hydrides and fluorides is one of them. In this article, the geometry structures and electronic properties of two kinds of fullerene derivatives have been investigated by density functional theory calculations.First of all, the generalized gradient approximation (GGA) based on density functional theory is used to analyze the geometric and electronic properties of the endohedral complexes M@C₂₀F₂₀ (M=Li, Na, Be, Mg). All M atoms are in the cage centre, and following the increase of the doped atomic number, the C-C bond distances become longer and longer, but C-F bond distances have little change. The doping energy of all M@C₂₀F₂₀ is negative that means the encapsulation would process under certain condition. The electronic structure calculations indicate that the valence electron of the M atoms transfer to the LUMO of C₂₀F₂₀, and make it to form new HOMO. Two distinct energy gap and magnetic properties emerge, among which the energy gap is very small with a net spin for doping Li or Na, but the energy gap is relatively large with no net spin for doping Be or Mg.In the last chapter, the geometric and electronic properties of C₈₀H₈₀ and H₂₀@C₈₀F₆₀ are studied. For C₈₀H₈₀, the most stable isomer is that 20 Hydrogens connecting 12 pentagons are inside, while the 60 others are outside the cage, confirming the correction of the "in-out" isomerism postulated by Saunders. In addition, H₂₀@C₈₀F₆₀ is expected to become a substitute for C₆₀F₆₀ due to it is a good stability. The electronic structure calculations show that the H atoms have the major and minor contributions to the higest occupied and the lowest unoccupied orbitals of the H₂₀@C₈₀H₆₀ respectively. However, the F atoms have the major and minor contributions to the higest occupied and the lowest unoccupied orbitals of the H₂₀@C₈₀F₆₀ respectively, while the H atoms have no contribution to the both HOMO and LUMO. In addition, the two Molecules of H₂₀@C₈₀H₆₀ and H₂₀@C₈₀F₆₀ show the character of the closed-shell structures with no magnetic moment.