We present an electromagnetic analogue of crystal (or ligand) field theory that describes geometric eigenmodes and the resonant plasmon wavelength in plasmonic nanocrystals in terms of a simple shape descriptor. Our model, crystal field plasmon splitting, is based on secular equations for geometric eigenmodes, allowing for the separation of pure shape from materials effects. As an example, the model is implemented to the experimental gold nanoparticles that undergo cube-to-sphere transition, showing that geometric eigenvalues change correspondingly in analogy to the atomic energy levels in Tanabe–Sugano correlation diagrams.

中文翻译：

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晶场等离激元分裂

我们提出了一种晶体（或配体）场论的电磁模拟物，它以简单的形状描述符描述了几何本征模式和等离激元纳米晶体中的共振等离激元波长。我们的模型（晶体场等离激元分裂）基于几何本征模态的长期方程，可以将纯形状与材料效果分开。例如，该模型适用于经历了立方体到球形过渡的实验金纳米颗粒，显示出几何特征值的变化类似于田边-S野相关图中的原子能级。