Thermal instability of silicon fullerenes stabilized with hydrogen: Computer simulation

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The structure and kinetic properties of a hollow single-layer fullerene-structured Si60 cluster are treated theoretically by molecular dynamic simulation in the temperature range 10 K ≤ T ≤ 1760 K. Five series of calculations are conducted, with simulation of several media inside and outside the Si60 cluster, specifically, vacuum and interior spaces filled with 30 and 60 hydrogen atoms with and without the exterior hydrogen environment of 60 atoms. The average radius of the silicon cluster, \( \bar R_{cl} \) increases with increasing temperature, reaching a maximal value in the absence of hydrogen near the cluster and taking smaller values if the unpaired bonds of silicon atoms are fully compensated with hydrogen atoms located inside the cluster and there is no exterior hydrogen “coat.” An increase in temperature yields a decrease in the average number of Si-Si bonds per atom in the silicon cluster, \( \bar n_b \), and in the average length \( \bar L_b \) of the Si-Si bonds. The higher stability of the quantities \( \bar n_b \) and \( \bar L_b \) in the entire temperature region under consideration is characteristic of the Si60 fullerene surrounded by a hydrogen “coat” and containing 60 hydrogen atoms in the interior space. Such clusters have smaller self-diffusion coefficients at high temperatures. The fullerene stabilized with hydrogen is stable to the formation of linear atomic chains up to the temperatures 270–280 K.