ABSTRACT
Carbon is a very remarkable element. It forms various kinds of different bonds not only with other atoms but also with atoms of its own kind. This latter feature can lead to polymers of amazing symmetry of which fullerenes and carbon nanotubes have recently gained much attention [1-5]. Furthermore, one has to realize that the familiar linear sp, triangular sp2, and tetrahedral sp3 bonds are just the limiting cases of carbon orbital arrangements — various intermediate forms exist as well. In fullerenes, for example, the surface curvature suggests a bond intermediate between sp2
and sp3, i.e. a spx (2< x<3) hybridization [6]. It certainly is not an accident that among the elements of the 4th group of the periodic table the versatile carbon — rather than silicon or any other member — forms the basis of life.
