Transition-Based Constrained DFT for the Robust and Reliable Treatment of Excitations in Supramolecular Systems.
Transition-Based Constrained DFT for the Robust and Reliable Treatment of Excitations in Supramolecular Systems.
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DOI：
10.1021/acs.jctc.1c00548
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发表时间：
2022-05-10
影响因子：
5.5
通讯作者：
Ratcliff, Laura E.
中科院分区：
文献类型：
--
作者：
Stella, Martina;Thapa, Kritam;Genovese, Luigi;Ratcliff, Laura E.
尽管可用的计算方法多种多样，但最先进的计算激发能的方法，如依赖于时间的密度泛函理论(TDDFT)，计算要求很高，因此仅限于中等规模的系统。这里，我们引入了一种新的约束DFT(CDFT)，其中约束对应于占用轨道和虚拟轨道之间的特定跃迁(T)或跃迁的组合，而不是像传统的CDFT那样对应于模拟空间的一个区域。我们比较了T-CDFT、TDDFT和ΔSCF对一组气相并烯分子和有机发光二极管发射体的低激发态(S1和T1)的结果，并与文献中的参考结果进行了比较。在理论的PBE水平上，T-CDFT在这两类分子上都优于ΔSCF，同时也被证明是更健壮的。对于Acenes中的局部激发，T-CDFT和TDDFT的表现是一样好的。对于OLED分子中的电荷转移(CT)类激发，T-CDFT也表现良好，相比之下，TDDFT的能量被严重低估。换句话说，T-CDFT同样适用于局域激发和CT态，以比TDDFT低得多的计算代价提供更可靠的激发能量。T-CDFT是为大型系统设计的，并已在线性缩放BigDFT码中实现。因此，它非常适合于探索显式环境对激发能量的影响，为未来模拟复杂现实形态中的激发态铺平道路，例如出现在OLED材料中的激发态。
Despite the variety of available computational approaches, state-of-the-art methods for calculating excitation energies, such as time-dependent density functional theory (TDDFT), are computationally demanding and thus limited to moderate system sizes. Here, we introduce a new variation of constrained DFT (CDFT), wherein the constraint corresponds to a particular transition (T), or a combination of transitions, between occupied and virtual orbitals, rather than a region of the simulation space as in traditional CDFT. We compare T-CDFT with TDDFT and ΔSCF results for the low-lying excited states (S1 and T1) of a set of gas-phase acene molecules and OLED emitters and with reference results from the literature. At the PBE level of theory, T-CDFT outperforms ΔSCF for both classes of molecules, while also proving to be more robust. For the local excitations seen in the acenes, T-CDFT and TDDFT perform equally well. For the charge transfer (CT)-like excitations seen in the OLED molecules, T-CDFT also performs well, in contrast to the severe energy underestimation seen with TDDFT. In other words, T-CDFT is equally applicable to both local excitations and CT states, providing more reliable excitation energies at a much lower computational cost than TDDFT cost. T-CDFT is designed for large systems and has been implemented in the linear-scaling BigDFT code. It is therefore ideally suited for exploring the effects of explicit environments on excitation energies, paving the way for future simulations of excited states in complex realistic morphologies, such as those which occur in OLED materials.
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