SPURIOUS STATES IN QUASI-PARTICLE THEORY

0+ spurious states arising due to the nonconservation of the number of particles, associated with the quasiparticle modified Tamm-Dancoff approximation method, up to the square of the number of particles operator are discussed. A procedure for eliminating the effects of these spurious states from the quasiparticle modified Tamm-Dancoff approximation basis states is prescribed and applied to structure studies of Ni isotopes employing the Kuo-Brown effective interaction, and the trends of the results thus obtained are compared with experiments and earlier calculations. © 1990 The American Physical Society.