Abstract :
Coulomb form factors for E0 transition in ^18O are discussed taking into account core-polarization effects. These effects are taken into account through the collective model of Tassie and also through a microscopic perturbation theory including excitations up to 2p1f shell. Space wave model functions defined for the orbits 1d5/2 , 2s1/ 2 and 1d3 /2 are obtained from the diagonalization of the interaction Hamilonian of Wildenthal. The calculations include the 0 2^+ state with excitation energies 3.6337MeV. The core – polarization effects which incorporate the collective model of Tassei describe the data very well for this state.