Effects of Molecular Orientational Disorder on the Electronic Structure of K3C60: With the Inclusion of the Tangentially Directed C σ-Orbital

Effects of molecular orientational disorder on the electronic structure of K3C60 are studied using a tight-binding model in which both the 2s and 2p orbitals of C atoms are taken into account. Nearly free of the cut-off distance of the interculster interaction and the form of the distance dependence of the hopping parameters, the orientational disorder always smears out the structure in the conduction-band density of states (DOS), while the value of the DOS at the Fermi level (N(EF)) changes slightly upon disordering. These results are in excellent agreement with the earlier ones based on the single molecular orbital approximation.