STRUCTURE AND PROPERTIES OF C-60 DIMERS BY GENERALIZED TIGHT-BINDING MOLECULAR-DYNAMICS

Recent Raman-scattering investigations of visible- or ultraviolet-irra diated solid C60 film have revealed that the film consists of photopol ymerized fullerene molecules with covalent intermolecular bonding in c ontrast to the weak van der Waals type bonding found in the crystal. I n this report various C60 dimer geometries are studied to determine th e most stable dimer configuration, using a recently developed generali zed tight-binding molecular-dynamics technique. Comparison of calculat ed properties with experimental results strongly suggests that the lin kage between C60 monomer units is across parallel double bonds reformi ng into a four-sided ring, giving a ''dumbbell'' structure.