Mansoori Kermani Maryam, Truhlar Donald G
Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States.
J Chem Theory Comput. 2024 Dec 10;20(23):10491-10506. doi: 10.1021/acs.jctc.4c01224. Epub 2024 Nov 19.
Metal clusters often have a variety of possible structures, and they are calculated by a wide range of methods; however, fully converged benchmarks on the energy differences of structures and spin states that could be used to test or validate these methods are rare or nonexistent. Small lithium clusters are good candidates for such benchmarks to test different methods against well-converged relative energetics for qualitatively different structures because they have a small number of electrons. The present study provides fully converged benchmarks for Li and Li clusters and uses them to test a diverse group of approximation methods. To create a dataset of well-converged single-point energies for Li and Li, stationary structures were optimized by Kohn-Sham density functional theory (KS-DFT) and then single-point energy calculations at these structures were carried out by two quite different beyond-CCSD(T) methods. To test other methods single-point energy calculations at these structures were carried out by KS-DFT, Mo̷ller-Plesset (MP) theory, coupled cluster (CC) theory, five composite methods (Gaussian-4, the Wuhan-Minnesota (WM) composite method, and the W2X, W3X, and W3X-L composite methods of Radom and co-workers), multiconfiguration pair-density functional theory (MC-PDFT), complete active space second-order perturbation theory (CASPT2), and -electron valence state second-order perturbation theory (NEVPT2). Our results show that rhomboid and trigonal bipyramid (TBP) geometries are the most stable structures for Li and Li, respectively. Using the W3X-L method to obtain our best estimates, the mean unsigned deviations were calculated for other methods for several structures and spin states of both Li and Li. Binding energies and diagnostics were calculated for all structures. The data in this paper are valuable for assessing the reliability of current electronic structure theories and also developing new density functionals and machine learned models.
金属团簇通常具有多种可能的结构，并且通过多种方法进行计算；然而，可用于测试或验证这些方法的关于结构和自旋态能量差的完全收敛的基准测试很少见或根本不存在。小锂团簇是进行此类基准测试的良好候选者，可针对定性不同结构的完全收敛的相对能量学来测试不同方法，因为它们的电子数量较少。本研究提供了锂和锂团簇的完全收敛基准，并使用它们来测试各种近似方法。为了创建锂和锂的完全收敛单点能量数据集，通过Kohn-Sham密度泛函理论（KS-DFT）优化了稳定结构，然后通过两种截然不同的超越CCSD(T)方法对这些结构进行单点能量计算。为了测试其他方法，在这些结构上通过KS-DFT、莫勒-普莱塞特（MP）理论、耦合簇（CC）理论、五种复合方法（高斯-4、武汉-明尼苏达（WM）复合方法以及拉多姆等人的W2X、W3X和W3X-L复合方法）、多组态对密度泛函理论（MC-PDFT）、完全活性空间二阶微扰理论（CASPT2）和电子价态二阶微扰理论（NEVPT2）进行单点能量计算。我们的结果表明，菱形和三角双锥（TBP）几何结构分别是锂和锂最稳定的结构。使用W3X-L方法获得我们的最佳估计值，计算了锂和锂的几种结构和自旋态的其他方法的平均绝对偏差。计算了所有结构的结合能和诊断值。本文中的数据对于评估当前电子结构理论的可靠性以及开发新的密度泛函和机器学习模型具有重要价值。
