Study of Soft Quadrupole Excitation in Nucleus ¹¹Li with Test Particle Method

The quadrupole excitations in nucleus ¹¹Li have been studied within the nuclear Vlasov equation approach. The classical phase space distribution function is given by the test particle propagation method. A soft mode of quadrupole excitation located around 2MeV is found. The total percentage of E2 energy-weighted sum rule exhausted in this soft resonance region is very sensitive to the extension of neutron halo in nucleus ¹¹Li. The results compared with other recent calculations are analyzed.