Effects of pairing, continuum and deformation on particles in the classically forbidden areas.

Particles in the classically forbidden areas are studied based on the deformed relativistic Hartree-Bogoliubov theory in continuum with PC-PK1 for magnesium isotopes. It is shown the deformation effect makes the number of particles in the classically forbidden areas increase. By analyzing the neutron and proton radii, it is found that the largest deviations from the empirical values appear at the predicted neutron halo nuclei $^{42}$Mg and $^{44}$Mg. Consistently, a notable increase at $^{42}$Mg and $^{44}$Mg is found in the total number of neutrons in the classically forbidden areas that includes the number of neutrons in continuum.