金属内包フラーレン生成の分子動力学シミュレーション (<小特集>マイクロスケールの流体・熱流動現象)

概要

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The growth process of metal-containing fullerene was studied by using the molecular dynamics method. Based on DFT (density functional theory) calculations of various forms of small clusters MC_n (M=La, Ni), multi-body potential functions between carbon and metal atoms were constructed with the Morse-type term and the Coulomb term as functions of coordinate number of a metal atom. The clustering process starting from 500 isolated carbon atoms and 5 metal atoms in a 342Å cubic cell was simulated under the controlled temperature condition at T_c=3000 K, and the growth history of metal-attached clusters was studied in detail. Fan-type structure was reproduced around the metal atom for MC_ (n<5), and mono-cyclic ring or bi-cyclic ring was observed for both La and Ni system. An open cap structure was formed around a lanthanum atom for LaC_n (20<n<50) due to the strong Coulomb interaction, while tangled-poly-cyclic structures and random cage were dominant for NiC_n (20<n<50). The lanthanum atom was completely enclosed in the carbon cage at the final stage, though the nickel atom attached on one face of the caged structure.
1999-02-25