The interaction between complex nuclei can be calculated by unifying the extended liquid drop model (ELDM) and the two center shell model (TCSM). The sudden and adiabatic approximations are discussed. The imaginary potential is calculated via the transition probability of the molecular states into the compound states. The dependence of the masses in fission and heavy ion scattering on the distance between the fragments seems to be very important. The O16-O16 and C12-C12 elastic and inelastic excitation functions are calculated and compared with experiments. The gross structure is interpreted as being due to virtual molecular states while a great part of the fine structure seems to be related to the excitation of quasibound nuclear molecules