A many-body microscopic band-mixing formulation of variation after projection of angular momentum and conservation of nucleon number is used to study the yrast band and first excitedK^π=0⁺ band in the doubly even nuclei^154,156Gd. The computed energy spectra and the interband and intra-band B (E2) values are in good agreement with corresponding experimental data. Connection with the phenomenological model of Stephens and Simon is discussed, bringing out the role played by thei_13/2 neutron pair in the microscopic formalism.

The odd-proton nucleus¹⁵⁵Tb and odd-neutron nucleus¹⁵⁵Dy are studied along with doubly-even nucleus¹⁵⁶Dy using microscopic method of variation after projection of angular momentum and conservation of nucleon number in each projected state. The calculated energies of the ground band in¹⁵⁶Dy and the ground and excited bands in¹⁵⁵Dy and¹⁵⁵Tb are in good agreement with the corresponding experimental data. The role played by thei_13/2 neutron pair in these nuclei is discussed.

The energy spectra of the even-parity (K^π = 2⁺, 3⁺) and odd-parity (K^π = 3⁻, 4⁻) side-bands in the doubly even nucleus¹⁷⁰Yb are studied in the framework of the microscopic method of variation after angular momentum projection with nucleon number conservation in each projected state. The calculated energy spectra of the ground band and the four side bands in¹⁷⁰Yb are in good agreement with the corresponding experimental results.