An efficient method is proposed for the calculation of the optical force of multiple nanoparticles. In this method, the optical force is calculated by integrating the Maxwell stress tensor (MST) over a closed surface encompassing the nanoparticle. The electromagnetic (EM) field required for evaluating the MST is computed with the coupling theory of quasinormal modes (QNMs), in which the EM field is expanded onto a small set of QNMs of each nanoparticle. Once these dominant modes, which are eigensolutions of source-free Maxwell equations with complex eigenfrequencies, are known, any variation of the interparticle distance, illumination polarization, or wavelength can be treated analytically. Comparisons with the full-wave numerical method demonstrate the accuracy and efficiency of the formalism. With the formalism, force maps are calculated at remarkable computation speed, providing a promising simulation tool for applications such as plasmon tweezer and photoinduced force microscopy.

中文翻译：

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基于准法向模式耦合理论的多个纳米粒子光力计算的有效方法

提出了一种计算多个纳米粒子光学力的有效方法。在该方法中，通过在包含纳米颗粒的封闭表面上对麦克斯韦应力张量 (MST) 进行积分来计算光学力。评估 MST 所需的电磁 (EM) 场是使用准正规模式 (QNM) 的耦合理论计算的，其中电磁场扩展到每个纳米颗粒的一小组 QNM。一旦知道这些主要模式，即具有复杂特征频率的无源麦克斯韦方程的特征解，粒子间距离、照明偏振或波长的任何变化都可以被分析处理。与全波数值方法的比较证明了形式主义的准确性和效率。用形式主义，