Method of projection operators in the two-rotor model

The Feshbach formalism of division of state space into two subspaces P and Q has been used to develop a two-rotor model of the nucleus, in the framework of which high-lying states can be excluded by projecting the wave functions on the space of low-lying bands (P space). Closed formulas are obtained for the reduced probabilities of electromagnetic E2 and M1 transitions. An analysis is made of nonadiabatic effects in the 230Th nucleus. It is shown that mixing of P and Q spaces has a fundamental role for M1 transitions between states of the low-lying bands. The calculated values of the energies and the ratios of the reduced probabilities of E2 transitions are in satisfactory agreement with experiment