Stability, electronic structure and reactivity of the polymerized fullerite forms

A study of band structure, stability and electron density distribution from selected crystal orbitals of polymerized C-60 forms was carried out. Linea r chain, tetragonal and hexagonal layers, and three-dimensional (3D) polyme r with a simple cubic lattice were calculated using an empirical tight-bind ing method. The hopping parameters were chosen to fit a theoretical X-ray e mission spectrum of C-60 to the experimental one. Our results indicate that all calculated polymers are semiconductors with the smallest energy gap fo r hexagonal structure. Though the molecules C-60 are linked by strong coval ent bonds, the crystal orbitals characterized by the electron density local ization on an individual carbon cage are separated in the electronic struct ure of polymers. The suggestions about reactivity of the 1D and 2D tetragon al polymers were made from the analyses of crystal orbitals accompanied wit h the highest occupied (HO) and lowest unoccupied (LU) bands. The polymeriz ed C-60 forms were found to be less stable than an icosahedral fullerene mo lecule. (C) 2000 Elsevier Science Ltd. All rights reserved.