Recent experimental techniques enable the nanoparticles' (NPs) ensembles to be made with an angstrom-level of interparticle gap widths. The theoretical description of their optical properties becomes more challenging because of the nonnegligible quantum mechanism (QM) effects such as electron tunneling and nonlocal screening. To demonstrate the microscopic mechanism of QM effects and quantitatively elucidate their impact on a variety of surface plasmon resonance (SPR) models of gold particle oligomers, in this work we performed a theoretical study on closely spaced Au cluster dimers and NP oligomers by the first-principles approach, and the classical or quantum-corrected electromagnetic models (CEM or QCM), respectively. Through the first-principles calculation on a series of AuN dimers with different interparticle distances d and N, we depicted the variation of the possibility of direct electron tunneling (DET) across the junction constructed by two nearest NPs with d and N, and found that it exactly follows an exponential decay and the decay rate linearly varies with 1/N. The impact of the QM effect on the SPR models excited along the dimer axis is much more profound than those perpendicular to the dimer axis. CEM/QCM calculations on strongly coupled NP dimers and symmetric and asymmetric trimers demonstrated the evolution of their optical properties with variable NP sizes, gap separations and light polarization, as well as the QM effect on the major SPR modes. The side-by-side comparison between the results from time-dependent density functional theory and CEM/QCM models sheds light on understanding the origin of a variety of SPR models of gold NP oligomers and the QM effect on those modes, and makes a connection between the calculations of small cluster and large NP oligomers.

中文翻译：

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揭示了电子隧穿对紧密排列的金粒子的等离子体共振的影响。

最新的实验技术使纳米粒子（NPs）的集合体能够以埃级的粒子间间隙宽度进行制作。由于不可忽略的量子机制（QM）效应（例如电子隧穿和非局部屏蔽），对其光学特性的理论描述变得更具挑战性。为了证明QM效应的微观机制并定量阐明其对金粒子低聚物的各种表面等离振子共振（SPR）模型的影响，在这项工作中，我们通过以下方法对紧密间隔的Au簇二聚体和NP低聚物进行了理论研究：原理方法，以及经典或量子校正的电磁模型（CEM或QCM）。通过对一系列具有不同粒子间距离d和N的AuN二聚体的第一性原理的计算，我们描绘了通过两个最接近的d和N NP所构成的结的直接电子隧穿（DET）可能性的变化，发现它恰好遵循指数衰减，衰减速率线性变化为1 / N。QM效应对沿二聚体轴激发的SPR模型的影响远大于垂直于二聚体轴的SPR模型的影响。对强耦合NP二聚体以及对称和不对称三聚体的CEM / QCM计算表明，随着NP尺寸，缝隙间距和光偏振的变化，它们的光学性能也得到了发展，以及QM对主要SPR模式的影响。