SOFT GIANT-DIPOLE MODE OF LI-11

The low-lying electric dipole distribution for Li11 is examined in detail in a large basis nonspurious shell model which includes up to 3Latin small letter h with stroke of excitation. A very strong enhancement of the E1 strength between 1 and 4 MeV of excitation is predicted when Woods-Saxon single-particle wave functions are used. The relativistic Coulomb excitation cross section is underestimated. However, an analysis of the contributions to the E1 matrix elements indicates that small changes in the structure of the low-lying states can lead to a significant increase in the predicted E1 strengths, so that excitations normally omitted from shell-model calculations are not necessarily needed to explain the anomalous Coulomb cross section. © 1990 The American Physical Society.