High- K isomers are excited metastable excitations that are found amongst the rotational states of deformed atomic nuclei. They exemplify the coexistence of single-particle and collective degrees of freedom. We review their properties and their theoretical description based on extensions of the Nilsson–Strutinsky approach. Emphasis is given to the limits of K -isomer existence, exotic shapes, fission, K -isomer collective rotations, and the possibilities for isomer manipulation.

Phase transition in odd-N isotopes 99,101,103 Pd are investigated via the E-GOS (E-Gamma Over Spin) curves, which strongly suggest a structure evolution from vibration to rotation along the yrast lines with increasing spin. Theoretical calculations have been performed for the ground state bands of 99,101,103 Pd in the framework of the cranked shell model (CSM) and the alignment properties observed experimentally are analyzed employing this model. The results show that the phase transition in the ground state bands of 99,101,103 Pd can be interpreted as the valence nucleons start to occupy the g 9/2 proton orbitals with increasing spin which would polarize the core to a small, but rigid quadrupole deformation.

Total Routhian Surface (TRS) calculations have been performed to investigate shape coexistence and evolution in neutron-deficient krypton isotopes 72,74,76 Kr. The ground-state shape is found to change from oblate in 72 Kr to prolate in 74,76 Kr, in agreement with experimental data. Quadrupole deformations of the ground states and coexisting 0 + 2 states as well as excitation energies of the latter are also well reproduced. While the general agreement between calculated moments of inertia and those deduced from observed spectra confirms the prolate nature of the low-lying yrast states of all three isotopes (except the ground state of 72 Kr), the deviation at low spins suggests significant shape mixing. The role of triaxiality in describing shape coexistence and evolution in these nuclei is finally discussed.