The DFT/MRCI method
The DFT/MRCI method
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DOI：
10.1002/wcms.1394
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
C. Marian;Adrian Heil;M. Kleinschmidt
中科院分区：
文献类型：
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作者：
C. Marian;Adrian Heil;M. Kleinschmidt
在过去的二十年中，密度泛函理论与多参考组态相互作用（DFT/MRCI）方法已经从计算大分子单重态和三重态激发态光谱性质的强有力方法发展成为适用于所有自旋多重态的更一般的多参考方法。在其原始公式中，它在评估主要来自局部单电子跃迁的单重态和三重态激发态方面表现出很高的效率。此外，DFT/MRCI是少数几种适用于大型系统的方法之一，可以在双激发起重要作用的扩展π系统中产生正确的状态排序。最近重新设计的DFT/MRCI哈密顿量将该方法的应用范围扩展到双发色团，如氢键或π堆叠二聚体和松散耦合的供体-受体系统。结合分子轨道的受限开放壳层Kohn-Sham优化，甚至可以解决电子激发的双重态和四重态。在简要概述了这种半经验方法背后的一般思想并简要回顾了结合密度泛函和多参考波函数理论的替代方法之后，给出了DFT/MRCI哈密顿矩阵元的公式，并讨论了双电子贡献的调整。DFT/MRCI变体的性能对实验或从头算参考数据的有机分子和过渡金属化合物的激发能进行了分析和案例研究，显示了该方法的优势和局限性。最后，对DFT/MRCI波函数的性质和进一步的发展进行了概述。
In the past two decades, the combined density functional theory and multireference configuration interaction (DFT/MRCI) method has developed from a powerful approach for computing spectral properties of singlet and triplet excited states of large molecules into a more general multireference method applicable to states of all spin multiplicities. In its original formulation, it shows great efficiency in the evaluation of singlet and triplet excited states which mainly originate from local one‐electron transitions. Moreover, DFT/MRCI is one of the few methods applicable to large systems that yields the correct ordering of states in extended π‐systems where double excitations play a significant role. A recently redesigned DFT/MRCI Hamiltonian extends the application range of the method to bi‐chromophores such as hydrogen‐bonded or π‐stacked dimers and loosely coupled donor–acceptor systems. In conjunction with a restricted‐open shell Kohn–Sham optimization of the molecular orbitals, even electronically excited doublet and quartet states can be addressed. After a short outline of the general ideas behind this semi‐empirical method and a brief review of alternative approaches combining density functional and multireference wavefunction theory, formulae for the DFT/MRCI Hamiltonian matrix elements are presented and the adjustments of the two‐electron contributions are discussed. The performance of the DFT/MRCI variants on excitation energies of organic molecules and transition metal compounds against experimental or ab initio reference data is analyzed and case studies are presented which show the strengths and limitations of the method. Finally, an overview over the properties available from DFT/MRCI wavefunctions and further developments is given.