Eur. Phys. J. A (2006) 30: 519-529
https://doi.org/10.1140/epja/i2006-10147-0

Nuclear Structure and Reactions

Improved BCS-type pairing for the relativistic mean-field theory

¹ Institute of Modern Physics, Chinese Academy of Science, 730000, Lanzhou, PRC
² School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, PRC
³ Research Center of Nuclear Theory of the Laboratory of Heavy Ion Accelerator of Lanzhou, 730000, Lanzhou, PRC
⁴ China Institute of Atomic Energy, 102413, Beijing, PRC
⁵ Institut für Theoretische Physik, Justus-Liebig-Universität, 35392, Giessen, Germany

Received: 7 February 2006
Accepted: 20 November 2006
Published online: 14 December 2006

Abstract

A density-dependent δ interaction (DDDI) is proposed in the formalism of BCS-type pairing correlations for exotic nuclei whose Fermi surfaces are close to the threshold of the unbound state. It provides the possibility to pick up those states whose wave functions are concentrated in the nuclear region by making the pairing matrix elements state dependent. On this basis, the energy level distributions, occupations, and ground-state properties are self-consistently studied in the RMF theory with deformation. Calculations are performed for the Sr isotopic chain. A good description of the total energy per nucleon, deformations, two-neutron separation energies and isotope shift from the proton drip line to the neutron drip line is found. Especially, by comparing the single-particle structure from the DDDI pairing interaction with that from the constant pairing interaction for a very neutron-rich nucleus it is demonstrated that the DDDI pairing method improves the treatment of the pairing in the continuum.