| Project/Area Number |
17540359
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Mathematical physics/Fundamental condensed matter physics
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| Research Institution | Kumamoto University |
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Principal Investigator |
SHIMOJO Fuyuki Kumamoto University, Graduate School of Science and Technology, Associate Professor, 大学院自然科学研究科, 助教授 (60253027)
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| Co-Investigator(Kenkyū-buntansha) |
ANIYA Masaru Kumamoto University, Graduate School of Science and Technology, Professor, 大学院自然科学研究科, 教授 (30221724)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Molten salt / Liquid / Halide / Noble metal / ab initio / First principles / Molecular dynamics / Simulation / 溶解塩 / ハロゲン / カルコゲン |
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| Research Abstract |
We have investigated the dynamic and electronic properties of molten noble-metal halides by ab initio molecular-dynamics simulations.
1. From the Calculations for molten CuI, we have confirmed that the nearest-neighbor distance for Cu-Cu pair is almost the same as that for Cu-I pair in spite of the correlation between the same type of ions. It has been shown that there exists a large fluctuation in the partial atomic concentration of Cu ions to retain the anomalously short Cu-Cu distance, while iodine ions distribute uniformly. It has been clarified by the population analysis that there is a covalent-like bonding between neighboring Cu ions as well as between Cu and I ions.
2. The pair distribution function for Ag-Ag pairs in molten AgI shows that there is a weak but clear Ag coordination shell around Ag iron s with an average interatomic distance, which is close to that for Ag-I pairs. As a result of such a short nearest-neighbor Ag-Ag distance, the density distribution of Ag ions fluctuates on an intermediate length scale of a few angstroms, which gives a hump in the structure factor at a wave vector of about 1 Å^<-1>. From population analysis, it has been revealed that there exists an interaction between Ag ions due to the electronic charges that spread over ions.
3. Corresponding to the recent X-ray scattering experiments, we have investigated the pressure dependence of the structural and electronic properties of molten AgI. It has been shown that the anomalously short Ag-Ag correlation is retained up to 20 GPa.
4. From the simulations for the superionic phase of Ag2Se, we have confirmed that Ag ions have the anomalous correlation as in noble-metal halides. By investigating the displacement-correlation functions between Ag ions, it has been clarified that Ag ions exhibit a collective motion with their neighbor Ag ions when they migrate between neighboring tetrahedral sites.
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