Genetic-algorithm prediction of the magic-number structure of(C60)Nclusters with a first-principles interaction potential

A genetic algorithm has been employed, in combination with the first-principles Pacheco-Ramalho intermolecular potential, not only including its two-body part but also its dominant three-body term, to predict the magic number structure of neutral $({\mathrm{C}}_{60}{)}_N$ clusters up to $N=25.\mathrm{}$ The calculated second finite difference of the total energy shows that the $({\mathrm{C}}_{60}{)}_N$ clusters with $N=7,$ 13, 18, and 22 are particularly stable. Present results indicate that the three-body effect is not significant for $({\mathrm{C}}_{60}{)}_N$ clusters with $N<~17,$ but above $N=17\mathrm{}$ we must consider the role played by the three-body dispersion term. It is found that $N=17\mathrm{}$ is a crossover from icosahedral to decahedral, and for $N>~23$ (inclusion of the three-body term) icosahedral structures are always lower in energy than decahedra.