Computation of diffuse scattering arising from one-phonon excitations in a neutron time-of-flight single-crystal Laue diffraction experiment.
Computation of diffuse scattering arising from one-phonon excitations in a neutron time-of-flight single-crystal Laue diffraction experiment.
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DOI：
10.1107/s1600576715010912
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发表时间：
2015-08-01
影响因子：
6.1
通讯作者：
von Zimmerman M
中科院分区：
文献类型：
--
作者：
Gutmann MJ;Graziano G;Mukhopadhyay S;Refson K;von Zimmerman M
提出了一种从密度泛函理论计算飞行时间中子单晶劳厄衍射实验中单声子激发漫散射的方法。以NaCl为例说明了这种方法。在中子飞行时间单晶劳厄衍射实验中，在NaCl单晶中观察到了声子的直接激发。在室温下，声子发射和激发离开漫散射的特征，这些都是很好地再现从头算声子密度泛函理论（DFT）。在20 K下的测量说明了声子的热布居的效果，留下对应于声子激发和强烈抑制声子湮灭的功能。 给出了一个配方来计算这些影响相结合的DFT结果与几何的中子实验。
A methodology is presented to compute diffuse scattering arising from one-phonon excitations in a time-of-flight neutron single-crystal Laue diffraction experiment from density functional theory results. This methodology is illustrated using NaCl as an example. Direct phonon excitation in a neutron time-of-flight single-crystal Laue diffraction experiment has been observed in a single crystal of NaCl. At room temperature both phonon emission and excitation leave characteristic features in the diffuse scattering and these are well reproduced using ab initio phonons from density functional theory (DFT). A measurement at 20 K illustrates the effect of thermal population of the phonons, leaving the features corresponding to phonon excitation and strongly suppressing the phonon annihilation. A recipe is given to compute these effects combining DFT results with the geometry of the neutron experiment.