Solid, liquid and gas structure of light nuclei

Nuclear systems are usually considered to be in the liquid phase, however, here we discuss the competition between the shell (liquid phase) and cluster structure in light neutron-rich nuclei. The appearance of molecular structure of α clusters with a geometric (equilateral triangular) shape is stabilized by the valence neutrons, and the nuclear systems with specific shapes are considered to be in the solid state. Also, α-condensed states originally suggested in ¹²C and ¹⁶O are extended to heavier nuclei with core nucleus, which are in the gas phase.