Stable polymers of C74 and C78 fullerenes

We report on new stable polymerized fullerites consisting of large fullerenes. Using the empirical many-body model potential for C atoms, we find that C74 and C78(C2v′) fullerenes possess stable infinite covalent networks in which C74 and C78 fullerenes form two-dimensional hexagonal lattice and one-dimensional chain, respectively. These phases are lower in energy than C60 polymers known to date. Moreover, in each case, the energy gain upon the interfullerene-bond formation is larger than that of the C60 polymer. Also their dimers, (C74)2 and (C78)2, are found to be highly stable. Based on the tight-binding study, they are both found to be semiconducting.