In this contribution, I will discuss two topics related to the clustering
of atomic nuclei. The first is dual character of the ground state. Recently,
it was pointed out that the ground states of atomic nuclei have dual character of
shell and cluster implying that both of the single-particle excitation and cluster
excitation occur as the fundamental excitation modes. The isoscalar monopole
and dipole transitions are regarded as the triggers to induce the cluster excitation.
By referring the Hartree-Fock and antisymmetrized molecular dynamics
calculations, the dual character and those transitions are explained. The second
is the linear-chain state of 16C in which the linearly aligned 3α particles
are sustained by the valence neutrons. The rather convincing evidences for this
exotic state are very recently reported by several experiments. Here, I introduce
a couple of theoretical analysis and predictions.
Keywords: Clustering of atomic nuclei, Unstable nuclei
