On the crystal structure of C36

We present calculations which indicate that the newly synthesized C-36 molecule most probably forms a Van der Weals crystal, of rhombohedral or hexagonal structure. Our results, based on intermolecular potentials of the atom-atom form, are in good agreement with the existing experimental evidence. Using covalent semiempirical potentials, we find that if molecules are placed closely together they tend to form extra bonds; several energy minima are thus obtained, but these correspond to structures with either too large or too short intermolecular distances in the basal plane. (C) 2000 Elsevier Science B.V. All rights reserved.