The Nuclear Incompressibility and Isoscalar Giant Dipole Resonance in Relativistic Continuum Random Phase Approximation

The isoscalar giant dipole resonance (ISGDR) in nuclei is studied in the framework of a fully self-consistent relativistic continuum random phase approximation (RCRPA). In this method the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single particle Green's function technique. We employ different type interactions (NL1, NL3, NL3^*, NL4, TM1, NLSH and PK1) corresponding to incompressibilities in the range 200–360 MeV. The results are discussed in comparison with the existing experimental data. It is found that the term η= 5/3<r²> can remove spurious components from the admixture of the center of mass state perfectly. The ISGDR distribution has two components, the lower-energy component and the higher-energy component. There is a large amount of very sharp peaks in the lower-energy region in RCRPA calculations. Only the higher-energy component is sensitive to the value of nuclear incompressibility employed in the calculations; the position of the lower-energy component is completely independent of the nuclear incompressibility K_nm.