2024/03/15 by Cong Wang, Wang, Cong
Physics and Astronomy · #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Solar and Space Plasma Dynamics
paper · pdf · doi:10.48550/arxiv.2403.10128
openalex publication_date 2024/03/15 · openalex created_date 2024/03/19 · openalex updated_date 2026/07/28
A general-order open-shell coupled-cluster method based on spatial orbitals is formulated. The method is an extension of the partial-spin adaptation (PSA) scheme from Janssen and Schaefer (Theor. Chim. Acta, 79, 1-42, 1991). By increasing the order of excitation operator and spin adaptation, the full configuration interaction (CI) limit is expected to be achieved. In the meanwhile, the advantages of spin-free approach in closed-shell systems: fourth-order truncation of the Baker-Campbell-Hausdorff (BCH) expansion and only HT-type connected terms are conserved.