ケイ酸塩融体の構造の分子運動論計算

概要

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The molecular dynamics (MD) calculations on silicate melts and glasses, assuming purely ionic potential functions of the Born-Mayer-Huggins type, have been successful so far in obtaining three-dimensional structures which are in harmony with observed data such as RDF and Raman spectra under ambient pressures. The increase in coordination number of silicon (from 4 to 6) was observed without change in potential parameters on compaction, accompanied by a 3-5 percent increase in the mean Si-O distance.<BR>The silicate systems, however, have their own difficulties : The mobility of ions is so small that the duration required to attain thermal equilibrium appears to be much longer than that for alkali halides (presumably by a factor of 100 to 1000), and the number of ions in the basic cell (usually 216 for alkali halides) might have to be much greater to permit full development of silicate framework without local strain concentration. The difficulties, which should render the calculation to be practically impossible in terms of available machine time and budget, make it inevitable to find suitable conditions (initial configuration, cooling rate, number of particles and so on) to give desired properties with reasonable accuracies within a reasonable machine time.
日本結晶学会の論文