Extending the Projection-Based Embedding Technique to Open-Shell Systems Using the Huzinaga Equation.

ABSTRACT: In this work, we present an approach for the embedding of wave function theory (WFT) and density functional theory (DFT) methods in a lower-level density functional approximation using the projection-based embedding (PbE) technique for open-shell systems. Our method is based on the Huzinaga equation, which is implemented in both spin-restricted and spin-unrestricted forms. While the unrestricted PbE approach has been previously reported in the literature and follows naturally from the theory for closed-shell systems, the restricted formulation required the development of a new theory, building on earlier work by Roothaan (Rev. Mod. Phys., 1960, 32, 179) as well as Shaik and Filatov (Chem. Phys. Lett., 1999, 304, 429). Our implementation allows for

SUBMITTER: Hegely B 

PROVIDER: S-EPMC12355723 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature