POLYMERIZED C-60 STUDIED BY FIRST-PRINCIPLES MOLECULAR-DYNAMICS

We have performed local-orbitals-based first-principles molecular-dynamical relaxations for seven different configurations of a C60 dimer. Of these seven, we find the dimer with adjacent C60's having parallel double bonds to be the only configuration having an energy lower than the energy of two isolated Ih C60's. We have computed the infrared frequencies and a Raman spectrum for this lowest-energy configuration, and we find these to be in agreement with the corresponding measured spectra of polymerized C60. The computed electronic eigenvalues and a simulation of the energy barrier to dimer separation are also compared with experiment. In addition, we have simulated an infinite linear chain of polymerized C60's, and we report the energy, the computed vibrational frequencies and Raman spectrum, and the electronic band structure. © 1994 The American Physical Society.