The KOALA program is presented, and its capabilities are discussed. KOALA is an ab initio code that uses Gaussian‐type basis sets with a focus on a treatment of wavefunction embedding methods, for which all subsystems can be relaxed with their corresponding wavefunction density. Among the key features of the program is a Davidson solver that is capable of treating, for example, both linear response for coupled‐cluster methods and density functional theory, as well as solving the Z‐vector equations for orbital‐relaxed ground‐state and excited‐state molecular properties. This solver is combined with frozen‐density embedding, which circumvents the problem of the steep scaling of conventional supermolecular correlation methods, enabling the computation of anisotropic environment effects without using semiempirical methods. A brief theoretical overview is given, and case studies for which the program could be used are discussed, as well as the efficiency for systems containing a total of hundreds of atoms, which can be divided into smaller subsystems.

中文翻译：

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KOALA程序：Wavefunction冻结密度嵌入

介绍了KOALA程序，并讨论了其功能。KOALA是使用高斯型基集的从头算代码，重点是波动函数嵌入方法的处理，为此，所有子系统都可以放宽其相应的波动函数密度。该程序的主要功能之一是戴维森求解器，该求解器能够处理耦合簇方法和密度泛函理论的线性响应，以及求解轨道松弛基态的Z矢量方程和激发态分子特性。该求解器与冻结密度嵌入相结合，从而避免了传统超分子相关方法的陡峭缩放问题，从而无需使用半经验方法即可计算各向异性环境效应。