Begam Khadiza, Bhandari Srijana, Maiti Buddhadev, Dunietz Barry D
Department of Physics, Kent State University, Kent, Ohio 44242, United States.
Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States.
J Chem Theory Comput. 2020 May 12;16(5):3287-3293. doi: 10.1021/acs.jctc.0c00086. Epub 2020 Apr 20.
Long range-corrected (LRC) or range-separated hybrid (RSH) functionals where the long-range (LR) limit of electronic interactions is set to the exact exchange have been shown to correct the tendency of traditional density functional theory (DFT) to underestimate the frontier orbital gap. Consequently, the use of such functionals in calculating electronic excited states using linear response based time-dependent DFT (TDDFT) has been successful in correcting the tendency for underestimating the energies of charge transfer states by DFT-based calculations. More recently formulations of functionals that attenuate the LR limit to address condensed-phase effects to polarize the electronic density have been reported. In particular screened RSH (SRSH) combined with polarizable continuum model (PCM) was benchmarked successfully in reproducing the fundamental gap and charge transfer state energies of molecular systems in the condensed phase. Here we use SRSH-PCM to address triplet excited states, and show its success in obtaining correspondence of the low-lying triplet states to the singlet-triplet gap in a similar way that the fundamental orbital gap corresponds to electron removal and addition energies. Importantly, the accuracy of the SRSH-PCM in calculating triplet excitations stands on the polarization consistent framework in addressing the scalar dielectric constant and affecting the optimal tuning by triplet energies. The prospect of even further improving the SRSH-PCM accuracy in calculating triplet states can be achieved by optimal tuning on the basis of the spin multiplicity gap.
长程校正（LRC）或范围分离混合（RSH）泛函，其中电子相互作用的长程（LR）极限被设定为精确交换，已被证明可纠正传统密度泛函理论（DFT）低估前沿轨道间隙的倾向。因此，在使用基于线性响应的含时DFT（TDDFT）计算电子激发态时，使用此类泛函已成功纠正了基于DFT的计算低估电荷转移态能量的倾向。最近，已报道了一些泛函的公式，这些公式减弱了LR极限以解决凝聚相效应，从而使电子密度极化。特别是，筛选后的RSH（SRSH）与极化连续介质模型（PCM）相结合，在再现凝聚相中分子系统的基本能隙和电荷转移态能量方面成功地进行了基准测试。在这里，我们使用SRSH-PCM来处理三重态激发，并展示了它在获得低三重态与单重态-三重态能隙对应关系方面的成功，其方式类似于基本轨道能隙与电子去除和添加能量的对应关系。重要的是，SRSH-PCM在计算三重态激发时的准确性基于极化一致框架，该框架用于处理标量介电常数并通过三重态能量影响最佳调谐。通过基于自旋多重度能隙的最佳调谐，可以实现进一步提高SRSH-PCM计算三重态的准确性的前景。
