Vibrations and potential energy surfaces (with Argonne V18) of4He and3He
A potential energy surface is constructed for3,4He with the two body Argonne V18 potential. The minimization suggests a semi rigid asymmetric top structure for4He, where the appropriate pointgroup symmetry is C 2. We calculate the Hessian matrix, determining the 6 normal modes of vibration (in the range 300 700 MeV) The breathing mode is found to lie at too high an energy to be observable and the nature of the excited states of the alpha particle at 20 MeV should probably be sought elsewhere. Similar investigations have been carried out for the A=3 system, finding a planar Cs configuration (scalene triangle) and three excited vibrational states (in the range 600 1900 MeV)