Quadrupole - quadrupole interaction calculations which include N = 2 mixing

We carry out a study of the study of the Q · Q interaction in a model space which consists of several nucleons in an open shell and all 2¯ hω excitations. Xo 2 Q · Q, where for t=1 we get the 'accepted strength'. In the 0p space, the spectrum would scale with t. In this space, the 2 + 1 and 2 + 2 states of 10 Be are degenerate, as are the [330] and [411] sets of J = 0 + , 1 + and 2 + triplets. When 2¯ hω admixtures are included, the degeneracies are removed. For t ≥ 1.8 we have new ground state and a new 2 + 1 state. These are states in which two particles are excited from the 0p to the 1s − 0d shell. There is no mixing of these 2p-2h states with the other states. For these 2p-2h states the occupancy for 0s,0p,1s-0d and 1p-of are 4,4,2 and 0 respectively.