Competition between different mechanisms of stability loss for the (C20)2 cluster dimer

The thermal stability of the (C₂₀)₂ cluster dimer consisting of two C₂₀ fullerenes has been numerically examined using the tight-binding method. The simulation of the dynamics of the (C₂₀)₂ dimer at temperatures of T = 2000–3500 K shows that the finite lifetime τ of this metastable system is determined by two fundamentally different processes: the decay of one of the C₂₀ fullerenes and the coalescence of two C₂₀ fullerenes to the C₄₀ cluster. The activation energies for these processes. E _a ≈ 3.4 and 2.7 eV, respectively, as well as their frequency factors, have been determined by analyzing the τ(T) dependence.