REGULAR AND IRREGULAR FEATURES OF CLASSICAL MOTION DESCRIBED BY A QUADRUPOLE BOSON HAMILTONIAN

A fourth-order quadrupole boson Hamiltonian H is treated semiclassical ly through a time-dependent variational principle. The variational fun ctions are coherent states for boson operators. In the parameters spac e of H there are regions, conventionally called ''nuclear phases,'' de termining specific static properties. Several ground states correspond ing to different equilibrium shapes are found as static solutions of c lassical equations of motion. The mechanism of destroying the tori of regular orbits and the onset of chaos depend on the nuclear phase. The regular and chaotic motions are analyzed in terms of Poincare section s and the largest Lyapunov exponent.