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. Linear chain, tetragonal and hexagonal layers, and three-dimensional (3D) polymer with a simple cubic lattice were calculated using an empirical tight-binding method. The hopping parameters were chosen to fit a theoretical X-ray emission spectrum of C-60 to the experimental one. Our results indicate that all calculated polymers are semiconductors with the smallest energy gap for hexagonal structure. Though the molecules C-60 are linked by strong covalent bonds, the crystal orbitals characterized by the electron density localization on an individual carbon cage are separated in the electronic structure of polymers. The suggestions about reactivity of the 1D and 2D tetragonal polymers were made from the analyses of crystal orbitals accompanied with the highest occupied (HO) and lowest unoccupied (LU) bands. The polymerized C-60 forms were found to be less stable than an icosahedral fullerene molecule. (C) 2000 Elsevier Science Ltd. All rights reserved.