フラーレン生成過程の分子動力学 : 第2報,完全なC_<60>へのアニーリング(熱工学,内燃機関,動力など)

概要

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The formation of a fullerene was simulated using the molecular dynamics method. The clustering process starting from 500 isolated carbon atoms was simulated under nearly equilibrium conditions at T_c-3000K with a density of 30 times lower than that in our previous study for investigation of the effect of annealing during collisions. The small clusters appeared in this simulation were simpler than those in the previous case; they were grown with a simple chain or ring structure for C_<n<20>, a 3-dimensional chaotic structure for around C_<20<n<40>, and a fullerene like caged structure for C_<n>40>. Since the density of carbon atoms in the simulation was still high due to the computational limitation, these clusters are expected to have a much longer collision free time in practice. For further evaluation of the effect of annealing, a C_<60> structure obtained from the simulation was annealed without collision at T_c=2500K. Through successive organized network transformations known as Stone-Wales rearrangement, a perfect fullerene-structured C_<60> was finally formed] in about 50ns. From the viewpoint of the Arrehenius type reaction rate of rearrangement, the high temperature of 2500K and the time-scale of 50ns for annealing were comparable to experimental conditions.
1997-07-25