Eur. Phys. J. A (2019) 55: 213
https://doi.org/10.1140/epja/i2019-12898-7

Regular Article - Theoretical Physics

Elimination of spurious modes before the solution of quasiparticle random-phase-approximation equations

¹ Institute of Particle and Nuclear Physics, Charles University, V Holešovičkách 2, 18000, Praha, Czech Republic
² Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511, Bratislava, Slovakia
³ Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
⁴ State University “Dubna”, 141980, Dubna, Moscow Region, Russia
⁵ Moscow Institute of Physics and Technology, 141701, Dolgoprudny, Moscow region, Russia

^* e-mail: nester@theor.jinr.ru

Received: 1 July 2019
Accepted: 26 September 2019
Published online: 18 November 2019

Abstract

A general method for the elimination of the spurious admixtures (SA) from two-quasiparticle (2qp) intrinsic nuclear excitations is proposed. It assumes the construction of 2qp configuration space with elements orthogonal to the given spurious mode. The method exploits Quasiparticle-Random-Phase-Approximation (QRPA) matrices but does not need a prior numerical solution of QRPA, i.e. SA-elimination occurs before QRPA equations are solved. After the refined basis is prepared, it can be used in the given matrix QRPA. The method is suitable for any type of spurious modes. We demonstrate the efficiency of the method for QRPA in axially deformed ¹⁵⁴Sm . The cases of SA arising from the center of mass motion ( states), nuclear rotation ( states), and pairing-induced violation of the particle number ( states) are considered. The method is compared with other SA-elimination schemes.