Isospin splitting of two particle-two hole states

If one attempts to express the isospin splittings of two particle-two hole states in terms of the energies of one particle-one hole states, then very bad answers come out if one limits oneself to very simple configurations for the 1p-1h states and chooses an interaction which will fit their energies. This may be viewed as a failure of the simple effective interaction method. In this work a formalism, which takes account of the complexity of the one particle-one hole states either in T.D.A. or R.P.A., is used. This may be regarded as extending the use of the R.P.A. to two particle-two hole states.