Ab Initio Molecular Dynamics Simulations and GIPAW NMR Calculations of a Lithium Borate Glass Melt

详细信息    查看全文

• 作者：Takahiro Ohkubo ; Eiji Tsuchida ; Takafumi Takahashi ; Yasuhiko Iwadate
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：April 14, 2016
• 年：2016
• 卷：120
• 期：14
• 页码：3582-3590
• 全文大小：561K
• 年卷期：0
• ISSN：1520-5207

文摘

The atomic structure of a molten 0.3Li₂O–0.7B₂O₃ glass at 1250 K was investigated using ab initio molecular dynamics (AIMD) simulations. The gauge including projector augmented wave (GIPAW) method was then employed for computing the chemical shift and quadrupolar coupling constant of ¹¹B, ¹⁷O, and ⁷Li from 764 AIMD derived structures. The chemical shift and quadrupolar coupling constant distributions were directly estimated from the dynamical structure of the molten glass. ¹¹B NMR parameters of well-known structural units such as the three-coordinated ring, nonring, and four-coordinated tetrahedron were found to be in good agreement with the experimental results. In this study, more detailed classification of B units was presented based on the number of O species bonded to the B atoms. This highlights the limitations of ¹¹B NMR sensitivity for resolving ¹¹B local environment using the experimentally obtained spectra only. The ¹⁷O NMR parameter distributions can theoretically resolve the bridging and nonbridging O atoms with different structural units such as nonring, single boroxol ring, and double boroxol ring. Slight but clear differences in the number of bridging O atoms surrounding Li that have not been reported experimentally were observed in the theoretically obtained ⁷Li NMR parameters.