Commutators method for Boson mapping in the seniority scheme

Débora Peres Menezes, Dennis Bonatsos A, Abraham Klein

Dennis Bonatsos A, Abraham Klein

P. Navrátil, H. B. Geyer

Hitoshi Nakada, A. Arima

Jan Dobeš, P. Navrátil, Olaf Scholten

Two approaches to the microscopical derivation of the interacting boson model are examined and compared. The first one is the well-known Otsuka-Arima-Iachello method as extended to a multishell case by using the generalized seniority scheme or exact calculations in the seniority equal to 0 and 2 space. The second one is a procedure based on the similarity transformed Dyson mapping. Close agreement between the two approaches is found.

P. Navrátil, Jan Dobeš

Methods of boson mapping are tested in calculations for a simple model system of four protons and four neutrons in single-j distinguishable orbits. Two-body terms in the boson images of the fermion operators are considered. Effects of the seniority v=4 states are thus included. The treatment of unphysical states and the influence of boson space truncation are particularly studied. Both the Dyson boson mapping and the seniority boson mapping as dictated by the similarity transformed Dyson mapping do not seem to be simply amenable to truncation. This situation improves when the one-body form of the seniority image of the quadrupole operator is employed. Truncation of the boson space is addressed by using the effective operator theory with a notable improvement of results.