Bois Juliana, Körzdörfer Thomas
Institut für Chemie, Universität Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany.
J Chem Theory Comput. 2017 Oct 10;13(10):4962-4971. doi: 10.1021/acs.jctc.7b00557. Epub 2017 Sep 15.
GW calculations for predicting vertical ionization potentials (IPs) and electron affinities of molecules and clusters are known to show a significant dependence on the density functional theory (DFT) starting point. A number of nonempirical procedures to find an optimal starting point have been proposed, typically based on tuning the amount of HF exchange in the underlying hybrid functional specifically for the system at hand. For the case of π-conjugated molecular chains, these approaches lead to a significantly different amount of HF exchange for different oligomer sizes. In this study, we analyze if and how strongly this size dependence affects the ability of nonempirical tuning approaches to predict accurate IPs for π-conjugated molecular chains of increasing chain length. To this end, we employ three different nonempirical tuning procedures for the GW starting point to calculate the IP of polyene oligomers up to 22 repeat units and compare the results to highly accurate coupled-cluster calculations. We find that, despite its size dependence, using an IP-tuned hybrid functional as a starting point for GW yields excellent agreement with the reference data for all chain lengths.
已知用于预测分子和团簇垂直电离势（IPs）和电子亲和能的GW计算对密度泛函理论（DFT）起点表现出显著依赖性。已经提出了许多非经验方法来找到最佳起点，通常是基于针对手头系统调整底层杂化泛函中HF交换的量。对于π共轭分子链的情况，这些方法导致不同寡聚物尺寸的HF交换量有显著差异。在本研究中，我们分析这种尺寸依赖性是否以及在多大程度上影响非经验调谐方法预测链长增加的π共轭分子链准确IPs的能力。为此，我们对GW起点采用三种不同的非经验调谐程序来计算多达22个重复单元的多烯寡聚物的IP，并将结果与高精度耦合簇计算进行比较。我们发现，尽管存在尺寸依赖性，但使用IP调谐的杂化泛函作为GW的起点，对于所有链长都与参考数据有很好的一致性。
