Higher Tamm-Dankoff approximation for rotational nuclear states

Within the Higher Tamm Dancoff Approximation (HTDA), single particle states associated with a mean field of the Hartree-Fock type are used into shell model like calculations. Recently, this approach has been used for ground state calculations in magic nuclei and in the N Z mass region, as well as to study properties of some important isomeric states. The Cranking version of this formalism (Cr. HTDA) represents an attempt to reproduce rotational bands up to high spins in heavy nuclei. In this context, through the use of the mean field part of HTDA, many deformation and rotation effects (as intruder orbitals and effects of the time reversal symmetry breaking) are included in the configuration space. This work discusses the Cr. HTDA results obtained for two Pb isotopes (in order to test the approach), when using up to 2 particles – 2 holes excitations and provides tests for enlargement of the configuration space by 4 particle – 4 holes excitations. It is focused on the configuration space properties, improvement of truncation schemes, computational problems and saturation behavior of some physical quantities.