We have developed and implemented a new ab initio code, Ceres (Computational Emulator of Rare Earth Systems), completely written in C++11, which is dedicated to the efficient calculation of the electronic structure and magnetic properties of the crystal field states arising from the splitting of the ground state spin‐orbit multiplet in lanthanide complexes. The new code gains efficiency via an optimized implementation of a direct configurational averaged Hartree–Fock (CAHF) algorithm for the determination of 4f quasi‐atomic active orbitals common to all multi‐electron spin manifolds contributing to the ground spin‐orbit multiplet of the lanthanide ion. The new CAHF implementation is based on quasi‐Newton convergence acceleration techniques coupled to an efficient library for the direct evaluation of molecular integrals, and problem‐specific density matrix guess strategies. After describing the main features of the new code, we compare its efficiency with the current state–of–the–art ab initio strategy to determine crystal field levels and properties, and show that our methodology, as implemented in Ceres, represents a more time‐efficient computational strategy for the evaluation of the magnetic properties of lanthanide complexes, also allowing a full representation of non‐perturbative spin‐orbit coupling effects. © 2017 Wiley Periodicals, Inc.

中文翻译：

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CERES：专门用于计算镧系元素配合物的电子结构和磁性的 ab initio 代码

我们开发并实现了一个新的 ab initio 代码，Ceres（稀土系统计算模拟器），完全用 C++11 编写，它致力于有效计算由镧系配合物中基态自旋轨道多重态的分裂。新代码通过优化实现直接配置平均 Hartree-Fock (CAHF) 算法提高效率，用于确定所有多电子自旋流形共有的 4f 准原子活性轨道，这些多电子自旋流形有助于镧系元素的地面自旋轨道多重态离子。新的 CAHF 实施基于准牛顿收敛加速技术，并结合了用于直接评估分子积分的有效库，和特定问题的密度矩阵猜测策略。在描述了新代码的主要特征后，我们将其效率与当前最先进的从头算策略进行比较，以确定晶体场水平和属性，并表明我们在 Ceres 中实施的方法代表了更多的时间-评估镧系元素配合物磁性的有效计算策略，还可以完整表示非微扰自旋轨道耦合效应。© 2017 威利期刊公司。代表了一种更省时的计算策略，用于评估镧系元素配合物的磁性，也允许完整表示非微扰自旋轨道耦合效应。© 2017 威利期刊公司。代表了一种更省时的计算策略，用于评估镧系元素配合物的磁性，也允许完整表示非微扰自旋轨道耦合效应。© 2017 威利期刊公司。