First-Principles Molecular Dynamics Simulation and Conductivity Measurements of a Molten xLi2O鈥?1 鈥?x)B2O3 System

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• 作者：Takahiro Ohkubo ; Eiji Tsuchida ; Mallory Gobet ; Vincent Sarou-Kanian ; Catherine Bessada ; Yasuhiko Iwadate
• 刊名：The Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：May 9, 2013
• 年：2013
• 卷：117
• 期：18
• 页码：5668-5674
• 全文大小：585K
• 年卷期：v.117,no.18(May 9, 2013)
• ISSN：1520-5207

文摘

The electronic properties and atomic structure of a molten xLi₂O鈥?1 鈥?x)B₂O₃ system were investigated by measuring conductivity and using first-principles molecular dynamics (MD) simulations. The conductivities obtained were converted to a Li self-diffusion coefficient D_蟽, using the Nernst鈥揈instein equation to assess charge transfer mechanisms. D_蟽 was compared with a Li self-diffusion coefficient, D_NMR, which we measured in a previous study using high-temperature pulsed field gradient NMR. The D_NMR/D_蟽 of xLi₂O鈥?1 鈥?x)B₂O₃ (0.2 鈮?x 鈮?0.5) at 1250 K ranged from 2.5 to 3.2, following the same trend as room temperature ionic liquids. First-principles MD simulations were performed using our own finite element density functional theory code, FEMTECK (finite element method-based total energy calculation) for molten xLi₂O鈥?1 鈥?x)B₂O₃ systems at 1250 K. We found that the O鈥揃鈥揙 angle distribution functions were characterized by a peak at approximately 120掳. Although the electron number from the electronic radial distribution function was arbitrary with regard to the cutoff distance, the net Li charge calculated from the integrated electron number surrounding Li was approximately 0.9 at 0.085 nm. The mean square displacement (MSD) of Li as a function of time was evaluated from the atomic configuration. Li self-diffusion coefficients calculated from the MSD were in better agreement with experimental results than they were using classical MD.