Dombrowski Dennis R, Schulz Timo, Kleinschmidt Martin, Marian Christel M
Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.
J Phys Chem A. 2023 Mar 2;127(8):2011-2025. doi: 10.1021/acs.jpca.2c07951. Epub 2023 Feb 17.
A reformulation of the combined density functional theory and multireference configuration interaction method (DFT/MRCI) is presented. Expressions for ab initio matrix elements are used to derive correction terms for a new effective Hamiltonian. On the example of diatomic carbon, the correction terms are derived, focusing on the doubly excited Δ state, which was problematic in previous formulations of the method, as were double excitations in general. The derivation shows that a splitting of the parameters for intra- and interorbital interactions is necessary for a concise description of the underlying physics. Results for L and L states in polyacenes and A and A states in mini-β-carotenoids suggest that the presented formulation is superior to former effective Hamiltonians. Furthermore, statistical analysis reveals that all the benefits of the previous DFT/MRCI Hamiltonians are retained. Consequently, the here presented formulation should be considered as the new standard for DFT/MRCI calculations.
提出了一种组合密度泛函理论与多参考组态相互作用方法（DFT/MRCI）的重新表述。使用从头算矩阵元的表达式来推导新有效哈密顿量的校正项。以双原子碳为例，推导了校正项，重点关注双激发Δ态，该态在该方法的先前表述中存在问题，一般的双激发也是如此。推导表明，为了简洁描述基础物理，有必要对轨道内和轨道间相互作用的参数进行拆分。多并苯中L和L态以及微型β-胡萝卜素中A和A态的结果表明，所提出的表述优于以前的有效哈密顿量。此外，统计分析表明，先前DFT/MRCI哈密顿量的所有优点都得以保留。因此，本文提出的表述应被视为DFT/MRCI计算的新标准。
