Elimination of spurious modes in quasiparticle random phase approximation


Seminar “Low-energy nuclear physics”

Date and Time: Tuesday, 12 February 2019, at 11:00 AM

Venue: Lecture Hall (2nd floor), Bogoliubov Laboratory of Theoretical Physics

Seminar topic: «Elimination of spurious modes in quasiparticle random phase approximation»

Authors: A. Repko (Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia), J. Kvasil (Institute of Particle and Nuclear Physics, Charles University, Prague, Czech Republic), V.O. Nesterenko (Bogoliubov Laboratory of Theoretical Physics JINR)

Speaker: A. Repko


Mean-field calculations of ground and excited states of nuclei necessarily involve spontaneous symmetry breaking, which leads to certain artifacts in such calculations. In particular, the excited states, as obtained by Quasiparticle Random Phase Approximation (QRPA), contain one or more spurious modes, whose multipolarity is given by the broken symmetry, e.g. translational (E1), rotational (M1/E2) and particle-number symmetry, which is related to pairing (E0). Although QRPA, in theory, should lead to their complete separation from the physical modes, certain admixtures remain due to the finiteness of the employed configuration space. The talk will focus on the elimination of these admixtures by an universal approach, both before and after QRPA diagonalization. The results will be demonstrated for spherical and axial nuclei.