King Daniel S, Gagliardi Laura
Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States.
J Chem Theory Comput. 2021 May 11;17(5):2817-2831. doi: 10.1021/acs.jctc.1c00037. Epub 2021 Apr 16.
The past decade has seen a great increase in the application of high-throughput computation to a variety of important problems in chemistry. However, one area which has been resistant to the high-throughput approach is multireference wave function methods, in large part due to the technicalities of setting up these calculations and in particular the not always intuitive challenge of active space selection. As we look toward a future of applying high-throughput computation to all areas of chemistry, it is important to prepare these methods for large-scale automation. Here, we propose a ranked-orbital approach to select active spaces with the goal of standardizing multireference methods for high-throughput computation. This method allows for the meaningful comparison of different active space selection schemes and orbital localizations, and we demonstrate the utility of this approach across 1120 multireference calculations for the excitation energies of small molecules. Our results reveal that it is helpful to distinguish the method used to generate orbitals from the method of ranking orbitals in terms of importance for the active space. Additionally, we propose our own orbital ranking scheme that estimates the importance of an orbital for the active space through a pair-interaction framework from orbital energies and features of the Hartree-Fock exchange matrix. We call this new scheme the "approximate pair coefficient" (APC) method and we show that it performs quite well for the test systems presented.
在过去十年中，高通量计算在化学领域各种重要问题上的应用大幅增加。然而，多参考波函数方法一直难以采用高通量方法，这在很大程度上是由于设置这些计算的技术细节，特别是活性空间选择这一并非总是直观的挑战。当我们展望将高通量计算应用于化学所有领域的未来时，为这些方法实现大规模自动化很重要。在此，我们提出一种排序轨道方法来选择活性空间，目标是使多参考方法标准化以用于高通量计算。该方法允许对不同的活性空间选择方案和轨道定域化进行有意义的比较，并且我们在针对小分子激发能的1120次多参考计算中展示了这种方法的实用性。我们的结果表明，区分用于生成轨道的方法和根据对活性空间的重要性对轨道进行排序的方法是有帮助的。此外，我们提出了自己的轨道排序方案，该方案通过基于轨道能量和哈特里 - 福克交换矩阵特征的对相互作用框架来估计轨道对活性空间的重要性。我们将这种新方案称为“近似对系数”（APC）方法，并且我们表明它对于所呈现的测试系统表现良好。
