  Isospin symmetry of atomic nuclei is explicitly broken by the
charge-dependent interactions, primarily the Coulomb force. Within the nuclear
density functional theory, isospin is also broken spontaneously. We propose a
projection scheme rooted in a mean field theory, that allows the consistent
treatment of isospin breaking in both ground and exited nuclear states. We
demonstrate that this scheme is essentially free from spurious divergences
plaguing particle-number and angular-momentum restoration approaches.
Applications of the new technique include excited high-spin states in
medium-mass N=Z nuclei, such as superdeformed bands and many-particle-many-hole
terminating states.
