Abstract An extended elastic eigenvector approach for adatom interactions is applied to model nitrogen c(2x2) atom islands on Cu(001). Oscillating interactions between adatom monomers or dimers are considered. Attractive pair interactions of adatoms are able to describe agglomeration but fail to explain the size of islands. Multisite interactions created by dimers, however, can explain the size of islands if an interaction parameter is adjusted properly. Finite size islands are formed when repulsive monomer interactions are balanced by attractive monomer-dimer interactions. A simple model of nearest neighbor attraction and s − 3 repulsion is used as an example for the interaction parameter search. Previous experimental studies have shown that in the low coverage region nitrogen atoms agglomerate to isolated square islands of about 5 nm × 5 nm size with a c(2x2) structure. With increasing coverage those islands form regular patterns but do not touch below about 0.4 monolayers. Previous experiments and calculations have shown that the square island pattern show significant elastic effects. Different adatom structures within the nitrogen islands have been analyzed, a dimer step model is able to reproduce the experimentally found island size. This model requires a molecular bond between nitrogen adatoms forming dimers. The model is also used to compute elastic interactions between islands and to check it against the experimentally found island pattern. Shortcomings and limitations of the model are discussed and open questions are formulated.

中文翻译：

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使用弹性多位点相互作用模拟 Cu(001) 上氮 c(2x2) 岛的大小

摘要 将吸附原子相互作用的扩展弹性特征向量方法应用于模拟 Cu(001) 上的氮 c(2x2) 原子岛。考虑了吸附原子单体或二聚体之间的振荡相互作用。吸附原子的有吸引力的配对相互作用能够描述聚集，但无法解释岛屿的大小。然而，如果适当调整相互作用参数，由二聚体产生的多位点相互作用可以解释岛的大小。当排斥性单体相互作用被有吸引力的单体-二聚体相互作用平衡时，就会形成有限尺寸的岛。最近邻吸引和 s - 3 排斥的简单模型用作交互参数搜索的示例。先前的实验研究表明，在低覆盖率区域，氮原子聚集成具有 ac(2x2) 结构的约 5 nm × 5 nm 大小的孤立方形岛。随着覆盖率的增加，这些岛形成规则图案，但不会接触到低于约 0.4 个单层。先前的实验和计算表明，方形岛状图案显示出显着的弹性效应。已经分析了氮岛内的不同吸附原子结构，二聚体阶梯模型能够重现实验发现的岛大小。该模型需要形成二聚体的氮吸附原子之间的分子键。该模型还用于计算岛屿之间的弹性相互作用，并根据实验发现的岛屿模式对其进行检查。讨论了该模型的缺点和局限性，并制定了开放性问题。