LENNARD-JONES-POTENTIAL CALCULATION OF C-60 STAGE-ONE GRAPHITE

The potential energies per atom of pure graphite and of C60 stage-one graphite intercalation compound (GIC) are compared in a calculation based on summing pairwise a Lennard-Jones 12-6 potential between all mass points with parameters taken from previous calculations on pure graphite. The C atoms are treated as uniformly smeared onto rigid spheres and rigid planes. For graphite the potential has a minimum of -46 meV/atom at an interplanar spacing of 3.37 with a compressibility of 3.0×10-12 cm2/dyn. For the GIC, assuming a triangular C60 net, the minimum is -22 meV/atom occurring at both a C60-graphene and a C60-C60 nearest approach distance of 2.9. This distance is comparable to fcc C60 at room temperature. The calculated compressibility is 3.8×10-12 cm2/dyn. © 1994 The American Physical Society.