2024/01/23 by Zhen Li, Li, Zhen, N. A. Smirnova +1
Physics and Astronomy · #Advanced Chemical Physics Studies #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Nuclear Theory (nucl-th) #Nuclear physics research studies
paper · pdf · doi:10.48550/arxiv.2401.12691
openalex publication_date 2024/01/23 · openalex created_date 2024/01/25 · openalex updated_date 2026/08/01
Brillouin-Wigner (BW) perturbation theory is developed for both ground and excited states of open-shell nuclei. We show that with optimal partitioning of the many-body Hamiltonian proposed earlier by the authors [Z. Li and N. Smirnova, arXiv:2306.13629], one can redefine the BW perturbation series for a given state of the effective Hamiltonian in a small P-space to be converging under the condition that the energy of this state is below the lowest eigenvalue of the Hamiltonian matrix block belonging to the complement of the P-space, characterized by the same good quantum numbers as the state under consideration. Specifically, the BW perturbative calculations for the lowest Jπ states are always converging due to the variational principle. This property does hold for both soft and hard internucleon interactions in the harmonic oscillator basis. To illustrate this method and check the convergence behavior, we present numerical studies of low-energy spectra of 5,6,7Li using the Daejeon16 and bare N3LO potentials.