Berardo Enrico, Hu Han-Shi, Shevlin Stephen A, Woodley Scott M, Kowalski Karol, Zwijnenburg Martijn A
Department of Chemistry, University College London , 20 Gordon Street, WC1H 0AJ, London, United Kingdom.
William R. Wiley Environmental Molecular Science Laboratory, Battelle, Pacific Northwest National Laboratory , K8-91, P.O. Box 999, Richland, Washington 99352, United States.
J Chem Theory Comput. 2014 Mar 11;10(3):1189-1199. doi: 10.1021/ct4010273. Epub 2014 Feb 11.
We have investigated the suitability of Time-Dependent Density Functional Theory (TD-DFT) to describe vertical low-energy excitations in naked and hydrated titanium dioxide nanoparticles. Specifically, we compared TD-DFT results obtained using different exchange-correlation (XC) potentials with those calculated using Equation-of-Motion Coupled Cluster (EOM-CC) quantum chemistry methods. We demonstrate that TD-DFT calculations with commonly used XC potentials (e.g., B3LYP) and EOM-CC methods give qualitatively similar results for most TiO nanoparticles investigated. More importantly, however, we also show that, for a significant subset of structures, TD-DFT gives qualitatively different results depending upon the XC potential used and that only TD-CAM-B3LYP and TD-BHLYP calculations yield results that are consistent with those obtained using EOM-CC theory. Moreover, we demonstrate that the discrepancies for such structures originate from a particular combination of defects that give rise to charge-transfer excitations, which are poorly described by XC potentials that do not contain sufficient Hartree-Fock like exchange. Finally, we consider that such defects are readily healed in the presence of ubiquitously present water and that, as a result, the description of vertical low-energy excitations for hydrated TiO nanoparticles is nonproblematic.
我们研究了含时密度泛函理论（TD-DFT）用于描述裸露的和水合的二氧化钛纳米颗粒中的垂直低能激发的适用性。具体而言，我们将使用不同交换关联（XC）势获得的TD-DFT结果与使用运动方程耦合簇（EOM-CC）量子化学方法计算的结果进行了比较。我们证明，对于所研究的大多数TiO纳米颗粒，使用常用XC势（例如B3LYP）的TD-DFT计算和EOM-CC方法给出的定性结果相似。然而，更重要的是，我们还表明，对于相当一部分结构，TD-DFT根据所使用的XC势给出定性不同的结果，并且只有TD-CAM-B3LYP和TD-BHLYP计算产生的结果与使用EOM-CC理论获得的结果一致。此外，我们证明此类结构的差异源自特定的缺陷组合，这些缺陷会引发电荷转移激发，而不含足够类Hartree-Fock交换的XC势对此描述不佳。最后，我们认为在普遍存在的水的存在下，此类缺陷很容易修复，因此，对水合TiO纳米颗粒的垂直低能激发的描述不存在问题。
