Electronic couplings for molecular charge transfer: Benchmarking CDFT, FODFT, and FODFTB against high-level ab initio calculations
Electronic couplings for molecular charge transfer: Benchmarking CDFT, FODFT, and FODFTB against high-level ab initio calculations
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DOI：
10.1063/1.4867077
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发表时间：
2014-03-14
影响因子：
4.4
通讯作者：
Blumberger, Jochen
中科院分区：
文献类型：
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作者：
Kubas, Adam;Hoffmann, Felix;Blumberger, Jochen
我们介绍了一个电子耦合矩阵元(H-ab)数据库(HAB11)，用于11个pi-共轭有机同二聚体阳离子的电子转移。在多参考组态相互作用MRCI+Q理论、n电子价态微扰理论NEVPT2和(自旋分量尺度的)近似耦合团簇模型CC2下对该数据库进行了高水平从头算，以评估三种降低计算成本的密度泛函方法的性能，包括约束密度泛函理论(CDFT)、碎片轨道密度理论(FODFT)和自洽电荷密度泛函紧束缚(FODFTB)。我们发现，CDFT方法与含有50%Hartree-Fock交换的改进的PBE泛函相结合，对绝对H-ab值(平均相对无符号误差=5.3%)和指数距离衰减常数β(4.3%)都有最好的结果。CDFT与纯PBE相结合，由于过量电荷分布过于分散，高估了38.7%，而经济的FODFT和高性价比的FODFTB方法分别低估了37.6%和42.4%，这是因为忽略了给体和受体之间的相互作用。然而，误差是系统性的，通过对每种方法应用统一的比例因子，可以显著减少误差。对数据库外的二聚体，特别是旋转的噻吩二聚体和大到并五苯的二聚体的应用表明，相同的缩放程序显著改善了与有机半导体和DNA相关的较大的圆周率共轭体系的FODFT和FODFTB结果。(C)2014 AIP出版有限责任公司。
We introduce a database (HAB11) of electronic coupling matrix elements (H-ab) for electron transfer in 11 pi-conjugated organic homo-dimer cations. High-level ab inito calculations at the multireference configuration interaction MRCI+Q level of theory, n-electron valence state perturbation theory NEVPT2, and (spin-component scaled) approximate coupled cluster model (SCS)-CC2 are reported for this database to assess the performance of three DFT methods of decreasing computational cost, including constrained density functional theory (CDFT), fragment-orbital DFT (FODFT), and self-consistent charge density functional tight-binding (FODFTB). We find that the CDFT approach in combination with a modified PBE functional containing 50% Hartree-Fock exchange gives best results for absolute H-ab values (mean relative unsigned error = 5.3%) and exponential distance decay constants beta (4.3%). CDFT in combination with pure PBE overestimates couplings by 38.7% due to a too diffuse excess charge distribution, whereas the economic FODFT and highly cost-effective FODFTB methods underestimate couplings by 37.6% and 42.4%, respectively, due to neglect of interaction between donor and acceptor. The errors are systematic, however, and can be significantly reduced by applying a uniform scaling factor for each method. Applications to dimers outside the database, specifically rotated thiophene dimers and larger acenes up to pentacene, suggests that the same scaling procedure significantly improves the FODFT and FODFTB results for larger pi-conjugated systems relevant to organic semiconductors and DNA. (C) 2014 AIP Publishing LLC.