Ground States of Silicon-Multisubstituted Fullerene: First-Principles Calculations and Monte Carlo Simulations

We present a systematical study on the possible stable structures of C_60?xSi_x (x=1–12) fullerenes using first-principles calculations combined with Monte-Carlo simulations. The initial fullerenes randomly substituting with silicon atoms are firstly generated and then their total energies are calculated quickly. The ground-state structures are found by the annealing process where Si atoms exchange their positions with C atoms. The stable structures are finally obtained through first-principles calculations with high precision. For the cases with a small amount of Si atoms (x≤4), results similar to those report previously are achieved. Some new stable Si-doped fullerenes with more Si atoms are also predicated. The results show that Si atoms in the C_60?xSi_x (x≤4) fullerenes have a trend of segregation with C atoms. The minimum-energy structure changes from a chemical unstable state to a chemical stable state when x≥8.