Šulka Martin, Šulková Katarína, Dubecký Matúš
Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, Bottova 25, 91724 Trnava, Slovakia.
Department of Physics, Faculty of Science, University of Ostrava, 30. Dubna 22, 70103 Ostrava, Czech Republic.
J Chem Phys. 2024 Sep 21;161(11). doi: 10.1063/5.0223733.
We have recently introduced an original method for sharply partitioning the correlation energy into dynamic and non-dynamic contributions. This method is based on the node of the Hartree-Fock (HF) Slater determinant and the stochastic projector fixed-node diffusion Monte Carlo (FNDMC) method [Šulka et al., J. Chem. Theory Comput. 19, 8147 (2023)]. This approach addresses the challenge of dissecting correlation energy in quantum chemistry. Here, we present the first application of this technique to explore CASSCF correlation energy contributions in selected molecular systems such as BH, FH, F2, and H2-H2. The results show that correlation energies derived from the full-valence active space CASSCF method, often believed to describe mostly non-dynamic correlation effects, contain an extraneous, unwanted, system-dependent component that belongs to the dynamic correlation energy. The findings suggest that the new HF-node/FNDMC-based electron correlation energy decomposition method provides a useful complementary tool, enabling the detection of inherent challenges in distinguishing between dynamic and non-dynamic contributions to correlation energies within methods where precise dissection of these effects is not possible.
我们最近引入了一种将相关能精确划分为动态和非动态贡献的原创方法。该方法基于哈特里 - 福克（HF）斯莱特行列式的节点以及随机投影固定节点扩散蒙特卡罗（FNDMC）方法[舒尔卡等人，《化学理论与计算杂志》19, 8147 (2023)]。这种方法解决了量子化学中剖析相关能的挑战。在此，我们展示了该技术在探索选定分子体系（如BH、FH、F2和H2 - H2）中CASSCF相关能贡献方面的首次应用。结果表明，通常认为主要描述非动态相关效应的全价活性空间CASSCF方法所导出的相关能，包含一个属于动态相关能的、外来的、不需要的、与体系有关的成分。这些发现表明，基于HF节点/FNDMC的新电子相关能分解方法提供了一个有用的补充工具，能够在无法精确剖析这些效应的方法中，检测区分相关能的动态和非动态贡献时所存在的固有挑战。
