Theoretical investigations of homo- and heteronuclear bridged fullerene oligomers

We have applied a density-functional based non''-orthogonal tight-binding (DF-TB) method to study the structure, energetics, and vibrational properties of different [C60[n-oligomers (n = 2, 3, and 4) as well as C60 dimers partially bridged by oxygen atoms or a NH group. The applicability of the scheme for finding the ground state of these systems was carefully checked against more sophisticated methods including an all-electron, self-consistent (SCF) scheme based on the local-density-approximation (LDA), and the recently developed generalized-gradient approximation (GGA). We present Raman intensities for the vibrations of the C60 oligomers, obtained in the framework of the bond polarization model, and compare with recent experimental data. (orig.)