S. Itoh et al., STRUCTURE AND ENERGETICS OF GIANT FULLERENES - AN ORDER-N MOLECULAR-DYNAMICS STUDY, Physical review. B, Condensed matter, 53(4), 1996, pp. 2132-2140
We present a molecular-dynamics study of the energetics and structures
of very large carbon cage clusters, which has been performed using ti
ght-binding methods, both empirical and ab initio. The use of an order
-N scheme, which provides the solution of the electronic problem with
an effort proportional to the size of the system, allowed us to study
clusters with up to 3840 atoms. We have considered clusters with spher
ical and with toroidal topology, and systematically find that spherica
l clusters have lower energy than toroidal clusters of the same size.
However, the toroidal C-360 and larger clusters have lower energy per
atom than the fullerene C-60. Concerning the spherical fullerenes, we
show that, in all cases, their minimum energy shape is markedly polyhe
dral rather than spherical. The clusters present nearly flat faces bet
ween each three contiguous protruding pentagon sites. The surfaces are
nevertheless smooth, without sharp edges in the lines joining the pen
tagons, which would be present in a perfect truncated icosahedron. We
also discuss the energetics of the clusters as a function of their siz
e, and the validity of different functional forms proposed in the lite
rature.