Extreme location of F drip line and disappearance of the N=20 magic structure -: art. no. 011301

The drip line of F isotopes is discussed from the viewpoint of a unified description of exotic nuclei with N∼20. The structure of those nuclei is described by means of large-scale shell model calculations, most of which are Monte Carlo shell model. It is shown that, due to the narrowing of the N=20 shell gap towards smaller Z, the mixing among normal, intruder, and higher intruder configurations can be enhanced significantly, and can produce crucial effects, including the F drip line located extremely far from the O drip line. The feasibility of Monte Carlo shell model is demonstrated for systems with an odd number of fermions.