Different techniques for calculating effective operators within the framework of the shell model using the same effective interaction and the same excitation spaces are presented. Starting with the large-basis no-core approach, we compare the time-honored perturbation-expansion approach and a model-space truncation approach. Results for the electric quadrupole and magnetic dipole operators are presented for [Formula Presented]. The convergence trends and dependence of the effective operators on differing excitation spaces and Pauli [Formula Presented]-operators are studied. In addition, the dependence of the electric-quadrupole effective charge on the harmonic-oscillator frequency and the mass number, for [Formula Presented], is investigated in the model-space truncation approach.
ASJC Scopus subject areas
- Nuclear and High Energy Physics