Ground state correlations and anharmonicity of vibrations
  A consistent treatment of the ground state correlations beyond the random phase approximation including their influence on the pairing and phonon-phonon coupling in nuclei is presented. A new general system of nonlinear equations for the quasiparticle phonon model (QPM) is derived. It is shown that this system contains as a particular case all equations derived for the QPM early. New additional Pauli principle corrections resulting in the anharmonical shifts of energies of the two-phonon configurations are found. A correspondence between the generalized QPM equations and the nuclear field theory is discussed. 
A.P. Severyukhin (1), V.V. Voronov (1) and D. Karadjov (2) ((1)   Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna,...