Coordination numbers are among the central quantities to describe the local environment of atoms and are thus used in various applications such as structure analysis, fingerprints, and parameters. Yet, there is no consensus regarding a practical algorithm, and many proposed methods are designed for specific systems. In this work, we propose a scale-free and parameter-free algorithm for nearest neighbor identification. This algorithm extends the powerful Solid-Angle based Nearest-Neighbor (SANN) framework to explicitly include local anisotropy. As such, our Anisotropically corrected SANN (ASANN) algorithm provides with a fast, robust, and adaptive method for computing coordination numbers. The ASANN algorithm is applied to flat and corrugated metallic surfaces to demonstrate that the expected coordination numbers are retrieved without the need for any system-specific adjustments. The same applies to the description of the coordination numbers of metal atoms in AuCu nanoparticles, and we show that ASANN based coordination numbers are well adapted for automatically counting neighbors and the establishment of cluster expansions. Analysis of classical molecular dynamics simulations of an electrified graphite electrode reveals a strong link between the coordination number of Cs+ ions and their position within the double layer, a relation that is absent for Na+, which keeps its first solvation shell even close to the electrode.

中文翻译：

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解决方案和接口的无参数协调编号。

配位数是描述原子局部环境的中心量，因此可用于各种应用中，例如结构分析，指纹和参数。然而，关于实用算法尚无共识，许多提议的方法是为特定系统设计的。在这项工作中，我们提出了一种用于近邻识别的无标度和无参数算法。该算法扩展了功能强大的基于Solid-Angle的Nearest-Neighbor（SANN）框架，以明确包括局部各向异性。因此，我们的各向异性校正SANN（ASANN）算法提供了一种快速，可靠且自适应的方法来计算协调数。ASANN算法应用于平坦和波纹金属表面，以证明无需任何系统特定的调整即可检索到预期的配位数。AuCu纳米粒子中金属原子的配位数的描述也是如此，我们表明基于ASANN的配位数非常适合于自动计数邻居和建立簇扩展。对带电石墨电极的经典分子动力学模拟的分析显示，Cs +离子的配位数与它们在双层中的位置之间有很强的联系，而Na +则不存在这种关系，这使得其第一个溶剂化壳甚至更靠近电极。AuCu纳米粒子中金属原子的配位数的描述也是如此，我们表明基于ASANN的配位数非常适合于自动计数邻居和建立簇扩展。对带电石墨电极的经典分子动力学模拟的分析显示，Cs +离子的配位数与它们在双层中的位置之间有很强的联系，而Na +则不存在这种关系，这使得其第一个溶剂化壳甚至更靠近电极。AuCu纳米粒子中金属原子的配位数的描述也是如此，我们表明基于ASANN的配位数非常适合于自动计数邻居和建立簇扩展。对带电石墨电极的经典分子动力学模拟的分析显示，Cs +离子的配位数与它们在双层中的位置之间有很强的联系，而Na +则不存在这种关系，这使得其第一个溶剂化壳甚至更靠近电极。