Triaxial deformation of unstable nuclei in the relativistic mean-field theory

We study the properties of unstable nuclei including the possibility of triaxial deformation in the relativistic mean-field theory. We calculate the energy surfaces of various light mass nuclei: ¹⁶O, ⁴⁰Ca, ²⁰Ne, ²⁴Ne and ²⁴Mg and a series of even mass sulfur isotopes, in the βγ plane. We find the well-known spherical solution for the ¹⁶O and ⁴⁰Ca nuclei and strong prolate solutions for ²⁰Ne, ²⁴Ne and ²⁴Mg, which are in agreement with the experimental data and the non-relativistic density-dependent Hartree - Fock results. For the sulfur isotopes, we find that the energy minimum moves from a prolate shape below ⁴⁶S through triaxial shapes for ^48-52S to an oblate shape above ⁵⁴S.