IBFA-2 studies in several transitional regions

Odd-even nuclei are very complicated systems in which the collective and the single particle degrees of freedom overlap. An extension to odd-even nuclei has been developed within the framework of the IBA models. It has been called the IBFA model. In the calculations that have been done until now, a version of the model, in which no distinction between protons and neutrons is made, has been used. The authors present an IBFA model which includes, explicitly, the proton-neutron degree of freedom. It is called the IBFA-2 model. This model presents several advantages with respect to the previous IBFA-1 model: i) it is closely related to the microscopic spherical shell model, ii) it allows to look for isospin effect, iii) it is a suitable model to study properties which depend critically on the nature of the odd particle, and iv) the constant behaviour of the model parameters gives to the model an important predictive character that was not present in the IBFA-1