V. Nolting et Ws. Verwoerd, A QUANTUM-CHEMICAL INVESTIGATION OF FLUORINE IN C-60, Journal of physics and chemistry of solids, 58(11), 1997, pp. 1907-1912
Quantum chemical calculations based on the PM3 molecular Hamiltonian a
re reported investigating the optimum geometry for the implantation of
a fluorine atom in a C-60 molecule. Of he various sites investigated
we find the fluorine attached to the outside of the spherical shell en
ergetically most favourable. It is shown that in this configuration th
e F-atom partially destroys the delocalized electronic state of tile f
ullerene in its immediate vicinity creating a locally diamond-like geo
metry with C-C bonds of 1.53 Angstrom. Three other possible equilibriu
m sites are also found; F occupying a substitutional site, F in the ce
ntre of the C-60 molecule, and F at the centre of a C-C bond. Those im
plantation sites, however, all have substantially higher total energie
s. Investigating higher addition products of the form C60Fi, 1 less th
an or equal to i less than or equal to 60, we find an energy minimum a
t i approximate to 24. The total energy curve E-tot as a function of i
is qualitatively and to a large extent even quantitatively correctly
re,reduced by a simple model calculation containing only the C-F bindi
ng energy and the nearest neighbour interactions. (C) 1997 Elsevier Sc
ience Ltd.