THE STRUCTURES OF ENDOHEDRAL COMPLEXES BETWEEN C-60 AND ALKALI OR HALOGEN ATOMS, AND THE INTERACTIONS BETWEEN THEM - A THEORETICAL APPROACH

In this paper, some properties of endohedral complexes formed between C60 and alkali or halogen atoms, (Alk(@C60) (Alk = Li, Na, K, Rb, Cs) and (Hal@C60) (Hal = F, Cl, Br, 1), which include electronic structure s, stabilities, potential energies at different positions of the endoh edral atoms, cage radius changes and charge distributions, have been c omputed by the quantum-chemical EHMO/ASED method. The computational re sults show that the potential energies of the systems have minima when the endohedral atoms are put at the center of the C60 cage for K, Rb, Cs and F, Cl, Br, I, but the minimum points of the potential energies are at r approximately 1.6 angstrom for Li and at r approximately 1.3 angstrom for Na deviated from the cage center. The curves of potentia l energies along five different directions vary only a little, that is , the potential field is basically sphero-symmetrical in the C60 cage. It has been pointed out that the endohedral complex systems Of C60 wi th alkalis and halogens, (Alk@aC60) and (Hal@C60), can be separated in to two subsystems quite well, in which the interaction between the end ohedral atom and the C's of the C60 cage can be described with the (ex p-6-1) potential function.