SHAPE COEXISTENCE AND LOW-LYING COLLECTIVE STATES IN A-APPROXIMATE-TO-100 ZR NUCLEI

Collective quadrupole and octupole excitations in even Zr-94-00 nuclei are studied within the fully microscopic generator-coordinate method using a basis generated by the selfconsistent Hartree-Fock BCS method. Results with the effective interaction SkM correctly describe the ex perimentally observed spherical to deformed shape transition at A = 10 0. Properties of low-lying 0+, 2+ and 3- states are analysed. The meas ured B(E3) value of 65 single-particle units in Zr-96 is underestimate d in our calculations. Various aspects of our theoretical approach are discussed, including Skyrme force parametrization, treatment of pairi ng and one- versus two-dimensional description of octupole excitations .