We present a polarizable embedding quantum mechanics/molecular mechanics (QM/MM) framework for ground‐ and excited‐state Complete Active Space Self‐Consistent Field (CASSCF) calculations on molecules within complex environments, such as biological systems. These environments are modeled using the AMOEBA polarizable force field. This approach is implemented by integrating the OpenMMPol library with the CFour quantum chemistry software suite. The implementation supports both single‐point energy evaluations and geometry optimizations, facilitated by the availability of analytical gradients. We demonstrate the methodology by applying it to two distinct photoreceptors, exploring the impact of the protein environment on the structural and photophysical properties of their embedded chromophores.

中文翻译：

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一种使用 OpenMMPol 库和 Cfour 之间接口的可极化 CASSCF/MM 方法


我们提出了一个可极化嵌入量子力学/分子力学 （QM/MM） 框架，用于对复杂环境（如生物系统）中的分子进行基态和激发态完全有源空间自洽场 （CASSCF） 计算。这些环境使用 AMOEBA 极化力场进行建模。这种方法是通过将 OpenMMPol 库与 CFour 量子化学软件套件集成来实现的。该实现支持单点能量评估和几何优化，并通过解析梯度的可用性实现。我们通过将其应用于两种不同的光感受器来展示该方法，探索蛋白质环境对其嵌入发色团的结构和光物理特性的影响。