  Potential energy surfaces are calculated by using the most advanced
asymmetric two-center shell model allowing to obtain shell and pairing
corrections which are added to the Yukawa-plus-exponential model deformation
energy. Shell effects are of crucial importance for experimental observation of
spontaneous disintegration by heavy ion emission. Results for 222Ra, 232U,
236Pu and 242Cm illustrate the main ideas and show for the first time for a
cluster emitter a potential barrier obtained by using the
macroscopic-microscopic method.
