| Project/Area Number |
11640371
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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 |
物性一般(含基礎論)
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| Research Institution | NIIGATA UNIVERSITY |
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Principal Investigator |
IYETOMI Hiroshi Faculty of Science, Niigata University, Professor, 理学部, 助教授 (20168090)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Akira Niigata University, President, 学長 (40004329)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | APW method / Electronic state / superionic conductivity / Muffin-tin sphere / p-d hybridization / Noble-metal halides / parallel computing / Molecular dynamics / クーロン固溶体 / 価数揺動 / マフィン・ティン球 / 多重極分極率 / 分子動力学 |
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| Research Abstract |
We have made details of the variational Augmented Plane Wave (APW) method available to the public. The new method determines the Kohn-Sham (KS) potentials in the framework of the muffin-tin (MT) approximation through minimization of the total energy functional of a system, including the radii of the MT spheres. It was confirmed that the fundamental idea of the method was applicable to other electronic-structure calculation schemes such as the LMTO and ASW methods with adjustable parameters for the KS potentials. The variaional APW method was then applied to a series of noble-metal halides to demonstrate that combination of multipole polarizability of the d shell and weakness of the p-d hybridization plays a primary role in giving rise to the superionic conductivity. We introduced a new parameter, called generalized covalency, which quantifies the strength of hybridization between the p bands arising from the p states of host halogen atoms and the d bands from the d states of noble-metal atoms. The generalized covalency systematically explains the trend of ionic conductivity as shown by the compounds. We have also carried out the tight-binding (TB) calculations for the generalized covalency in the noble-metal compounds. Appropriate choice of the TB parameters leads to the essentially same results as those obtained by the first-principle calculations. Currently we are developing a molecular dynamics code based on the TB approximation that enables us to study the ionic transport in materials at the electronic level ; parallel computation based on the Message Passing Interface is within our scope. How to extract the TB parameters from the variational APW calculations is a remaining issue to be addressed.
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