AB-INITIO GEOMETRY AND STABILITY OF A C120 TORUS

Previously reported calculations using a Stillinger-Weber type potential have predicted a remarkable stability for carbon toroidal forms. Semi-empirical calculations indicate cohesive energies for the smaller tori near that of C60 and stabilities comparable to graphite for the larger tori. A comparison of the cohesive energies for the smallest of the proposed tori C120 with icosahedral C60 is presented as determined from ab initio calculations. The results substantiate the semi-empirical calculations by verifying that the cohesive energy of the C120 torus is comparable to that of buckminsterfullerene. Optimized geometries, Koopmans' ionization potentials and HOMO-LUMO separations are also reported and compared to values obtained for C60.