Periodic-DFT of a Disordered System: Mg2(FeH6)0.5(CoH5)0.5

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• 作者：Stewart F. Parker ; Stefano Deledda
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：December 6, 2012
• 年：2012
• 卷：116
• 期：48
• 页码：25206-25212
• 全文大小：552K
• 年卷期：v.116,no.48(December 6, 2012)
• ISSN：1932-7455

文摘

The quaternary hydride Mg₂[FeH₆]_0.5[CoH₅]_0.5 is a disordered material with a random distribution of the complex ions. In the present contribution, we use a combination of inelastic neutron scattering (INS) spectroscopy and periodic density functional theory (periodic-DFT) to further characterize this novel material. The calculations rationalize the difference in decomposition temperature for the compound relative to the parent compounds, Mg₂[FeH₆] and Mg₂[CoH₅]. We show that the complex ions behave as independent entities for the internal modes (stretch, bend): i.e., if the mode involves the [FeH₆]^4- ions, then the [CoH₅]^{4鈥?/sup> ions are largely at rest and vice versa. For the librations and translations, this is not so, and the modes involve both types of ion. The infrared spectra are surprisingly simple, but show a very strong band in the far-infrared that is typical of this type of system that has not previously been observed.}