Nonlocalized clustering in ^18O

The low-lying states ( J^π =0^+, 2^+ , and 4^+ ) of ^18O system are investigated by using the microscopic Generator Coordinate Method (GCM)-Brink wave functions, in which one simple picture of ^16O +^2n structure is assumed for investigating the character of relative motion of the core ^16O and the assumed dineutron cluster. By calculating the squared overlap between the GCM-Brink wave functions and the angular-momentum-projected Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave functions in a simple ^18O (^16O +^2n) model, it is found that the single THSR wave functions characterizing the nonlocalized clustering are almost equivalent to the corresponding GCM-Brink wave functions. The results indicate that the concept of nonlocalized clustering can be extended even in the more-shell-model-like states in nuclei.