PolymerizedC60studied by first-principles molecular dynamics

Abstract

We have performed local-orbitals-based first-principles molecular-dynamical relaxations for seven different configurations of a ${\mathrm{C}}_{60}$ dimer. Of these seven, we find the dimer with adjacent ${\mathrm{C}}_{60}$’s having parallel double bonds to be the only configuration having an energy lower than the energy of two isolated ${\mathit{I}}_{\mathit{h}}$ ${\mathrm{C}}_{60}$’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 ${\mathrm{C}}_{60}$. 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 ${\mathrm{C}}_{60}$’s, and we report the energy, the computed vibrational frequencies and Raman spectrum, and the electronic band structure.