144 research outputs found
Transformation of amorphous carbon clusters to fullerenes
Transformation of amorphous carbon clusters into fullerenes under high
temperature is studied using molecular dynamics simulations at microsecond
times. Based on the analysis of both structure and energy of the system, it is
found that fullerene formation occurs in two stages. Firstly, fast
transformation of the initial amorphous structure into a hollow sp shell
with a few chains attached occurs with a considerable decrease of the potential
energy and the number of atoms belonging to chains and to the amorphous domain.
Then, insertion of remaining carbon chains into the sp network takes place
at the same time with the fullerene shell formation. Two types of defects
remaining after the formation of the fullerene shell are revealed: 7-membered
rings and single one-coordinated atoms. One of the fullerene structures
obtained contains no defects at all, which demonstrates that defect-free carbon
cages can be occasionally formed from amorphous precursors directly without
defect healing. No structural changes are observed after the fullerene
formation, suggesting that defect healing is a slow process in comparison with
the fullerene shell formation. The schemes of the revealed reactions of chain
atoms insertion into the fullerene shell just before its completion are
presented. The results of the performed simulations are summarized within the
paradigm of fullerene formation due to selforganization of the carbon system.Comment: 35 pages, 9 figure
On the possibility to consider fullerene shell C60 as a conducting sphere
Correctness of the model representing the fullerene shell C60 as a conducting
sphere has been analyzed. The static and dynamical polarizabilities of the
molecule C60 have been calculated on the basis of experimental data on the
photo-absorption cross- section of fullerene. It has been shown that the real
C60 in the static electric field behaves most likely as a set of separate
carbon atoms rather than as a conducting sphere and its static polarizability
exceeds by more than two times that of conducting sphere.Comment: 5 pages, 2 figure
Localization of the valence electron of endohedrally confined hydrogen, lithium and sodium in fullerene cages
The localization of the valence electron of , and atoms enclosed
by three different fullerene molecules is studied. The structure of the
fullerene molecules is used to calculate the equilibrium position of the
endohedrally atom as the minimum of the classical -body Lennard-Jones
potential. Once the position of the guest atom is determined, the fullerene
cavity is modeled by a short range attractive shell according to molecule
symmetry, and the enclosed atom is modeled by an effective one-electron
potential. In order to examine whether the endohedral compound is formed by a
neutral atom inside a neutral fullerene molecule or if the valence
electron of the encapsulated atom localizes in the fullerene giving rise to a
state with the form , we analyze the electronic density, the
projections onto free atomic states, and the weights of partial angular waves
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