Dall'Osto Giulia, Gil Gabriel, Pipolo Silvio, Corni Stefano
Department of Chemical Sciences, University of Padova, via Marzolo 1, Padova, Italy.
Université de Lille, CNRS, Centrale Lille, ENSCL, Université d'Artois UMR 8181 Unité de Catalyse et Chimie du Solide, F-59000 Lille, France.
J Chem Phys. 2020 Nov 14;153(18):184114. doi: 10.1063/5.0022329.
Investigating nanoplasmonics in an explicit time-dependent perspective is a natural choice when light pulses are used and may also reveal aspects that are hidden in a frequency-based picture. In the past, we proposed a method time domain-boundary element method (TD-BEM) to simulate the time dependent polarization of nanoparticles based on a boundary element method that is particularly suitable to interface with a quantum atomistic description of nearby molecules. So far, however, metal dielectric functions in TD-BEM have been modeled through analytic expressions, such as those of Debye and Drude-Lorentz, which cannot account for multiple electronic resonances. Our approach allows us to include in the TD-BEM framework also the description of metals with complicate dielectric function profiles in the frequency domain. Particularly, among all metals, gold is a challenging case due to the presence of many transition frequencies. We applied our methods to different metals (gold, silver, and the less commonly investigated rhodium) and different shaped nanoparticles (spheres, ellipsoids, and cubes), the approach has been tested comparing TD-BEM and frequency domain BEM absorption spectra, and it has been used to investigate the time-dependent field acting locally close to nanoparticle vertices.
当使用光脉冲时，从显式的时间相关角度研究纳米等离子体是一种自然的选择，并且还可能揭示基于频率的描述中隐藏的方面。过去，我们提出了一种时域边界元方法（TD-BEM），以基于边界元方法模拟纳米颗粒的时间相关极化，该方法特别适合与附近分子的量子原子描述相结合。然而，到目前为止，TD-BEM中的金属介电函数是通过解析表达式建模的，例如德拜和德鲁德-洛伦兹表达式，这些表达式无法解释多个电子共振。我们的方法使我们能够在TD-BEM框架中纳入对频域中具有复杂介电函数分布的金属的描述。特别是，在所有金属中，由于存在许多跃迁频率，金是一个具有挑战性的例子。我们将我们的方法应用于不同的金属（金、银以及较少研究的铑）和不同形状的纳米颗粒（球体、椭球体和立方体），通过比较TD-BEM和频域BEM吸收光谱对该方法进行了测试，并用于研究纳米颗粒顶点附近局部作用的时间相关场。
