It is difficult to characterize by experiment the structural features of liquids and glasses which lack long-range translational periodicity in the structure. Here, we suggest that the height and shape of the first peak of the structure function $S\left(Q\right)$ carry significant information about the nature of the medium-range order and the coherence of density correlations. It is further proposed that they indicate how ideal the liquid structure is. Here, the ideal state is defined by long-range density correlations, not by structural coherence at the atomic level. The analysis is applied to the $S\left(Q\right)$ of metallic alloy liquids determined by x-ray diffraction and simulation. The ideality index defined here may provide a common parameter to characterize structural coherence among various disparate groups of liquids and glasses.

中文翻译：

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液体结构的理想性：以金属合金液体为例

通过实验难以表征液体和玻璃的结构特征，这些液体和玻璃的结构缺乏长距离的平移周期性。在这里，我们建议结构函数的第一个峰的高度和形状$\mathrm{小号}（问）$携带有关中程级性质和密度相关性一致性的重要信息。进一步建议它们指示液体结构的理想程度。在这里，理想状态是由远距离密度相关性定义的，而不是由原子级的结构相干性定义的。该分析适用于$\mathrm{小号}（问）$X射线衍射和模拟确定的金属合金液体的含量。此处定义的理想度指数可以提供一个通用参数，以表征液体和玻璃的各种不同组之间的结构一致性。