To understand oxidation in three-dimensional silicon, dynamic characteristics of a SiO x system with various stoichiometries were investigated. The calculated results show that the self-diffusion coefficient increases as oxygen density decreases, and the increase is large when the temperature is low. It also shows that the self-diffusion coefficient saturates, when the number of removed oxygen atoms is sufficiently large. Then, approximate analytical equations are derived from the calculated results, and the previously reported expression is confirmed in the extremely low-SiO-density range.

The pressure and SiO-incorporation effect on the temperature dependence of dynamical properties for silicon oxide (SiO2)1−x(SiO)x is theoretically studied by first-principles molecular dynamics. It is found that the incorporation of SiO enhances the selfdiffusions even under high pressure. The SiO effect on Si selfdiffusion is however reduced by the pressure at temperature lower than 4000 K, and the amount of reduction is larger for lower temperature, while the effect on O selfdiffusion is hardly reduced, being independent of the temperature. Such a difference is thought to come from the difference in selfdiffusion mechanisms between Si and O. It is indicated that the incorporated SiO acts as combined SiO interstitials rather than separate Si interstitials or O vacancies. This also suggests that the oxide viscous flow mechanism is a promising candidate for the origin of the Si missing in oxidizing Si nanopillars.

The stereochemical course of the methoxymercuration-demercurations and the 1,3-dipolar cycloadditions of mesitonitrile oxide on the exocyclic double bonds of 2,4-dimethyl-7-methylenetetracyclo[3.3.0.0.2,804,6]octan-3-one (4a), its corresponding exo-3-ol (4b), endo-3-ol (4c), and 2,3,4-trimethyl-7-methylenetetracyclo[3.3.0.0.2,804,6]octan-3-exo-ol (4d) were investigated. In the methoxymercurations of 4a and 4b, the methoxyl group was incorporated in the exo and endo positions, with endo preferred over exo. On the other hand, 4c and 4d underwent the stereospecific incorporation of the methoxyl group in the endo position. In the 1,3-dipolar cycloadditions, 4a or 4b afforded exo- and endo-adducts, with the exo-adduct preferred. These results seem to imply similar stereochemical course of the formation of the mercurinium-ion intermediates and the 1,3-dipolar cycloadditions. The results are discussed on the basis of the steric hindrance of the molecular framework and the substituents which are located at the C-3 position.

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