- 著者
- Boero Mauro Parrinello Michele Terakura Kiyoyuki Ikeshoji Tamio Liew Chee Chin
- 出版者
- American Physical Society
- 雑誌
- Physical review letters (ISSN:00319007)
- 巻号頁・発行日
- vol.90, no.22, pp.226403, 2003-06
- 被引用文献数
- 157 118
A first principles study of a hydrated electron in water at ordinary and supercritical conditions is presented. In the first case, the electron cleaves a cavity in the hydrogen bond network in which six H2O molecules form the solvation shell. The electron distribution assumes an ellipsoidal shape, and the agreement of the computed and the experimental optical absorption seems to support this picture. At supercritical conditions, instead, the H-bond network is not continuous and allows us to predict that the electron localizes in preexisting cavities in a more isotropic way. Four water molecules form the solvation shell but the localization time shortens significantly.
- 著者
- Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi
- 出版者
- American Physical Society
- 雑誌
- Physical review letters (ISSN:00319007)
- 巻号頁・発行日
- vol.91, no.20, pp.206401, 2003-11
- 被引用文献数
- 27 22
The displacement of an oxygen atom in pure α quartz is studied via first-principles molecular dynamics. The simulations show that when an O atom in a Si-O-Si bridge is moved away from its original equilibrium position, a new stable energy minimum can be reached. Depending on the spin state and charge Q of the system, this minimum can give rise to either a threefold oxygen (singlet ground state and Q=+1) or to an unsaturated Si atom carrying a dangling bond (triplet state). In the latter case, the hyperfine parameters associated with the 29Si dangling bond are in rather good agreement with electron paramagnetic resonance/electron nuclear double resonance experiments.
- 著者
- Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi Murakami Kouichi
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.86, no.20, pp.201910, 2005-05
- 被引用文献数
- 17 18
Recent experiments have shown that pure Si structures in a matrix of SiO2 can be formed by electron excitation techniques, with appealing applications in nanotechnology. Our ab initio simulations provide an insight into the underlying mechanism, showing that electron excitations weaken Si–O bonds in SiO2, dislodge O atoms and allow Si dangling bonds to reconstruct in stable Si–Si structures below the melting temperature. Differences in diffusivity of O (fast) and Si (slow) are shown to play a decisive role in the process.
- 著者
- Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi Murakami Kouichi
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.86, pp.201910, 2005-05
- 被引用文献数
- 17
Recent experiments have shown that pure Si structures in a matrix of SiO2 can be formed by electron excitation techniques, with appealing applications in nanotechnology. Our ab initio simulations provide an insight into the underlying mechanism, showing that electron excitations weaken Si–O bonds in SiO2, dislodge O atoms and allow Si dangling bonds to reconstruct in stable Si–Si structures below the melting temperature. Differences in diffusivity of O (fast) and Si (slow) are shown to play a decisive role in the process.
- 著者
- 寺倉 清之 池田 隆司 Boero Mauro
- 出版者
- 北海道大学低温科学研究所
- 雑誌
- 低温科学 (Low temperature science) (ISSN:18807593)
- 巻号頁・発行日
- vol.64, pp.57-69, 2006-03-22
多様な状況下で多様な振る舞いを示す水の性質の解明は,長い研究の歴史にも拘らず,なお物理化学, 生物の主要な研究課題となっている.第一原理分子動力学法に基づく計算機シミュレーションによる 水の研究から,水の基本的性質,超臨界水の物理と化学,高圧下のメタンハイドレードなどについて 解説する.