An analysis of E(5) shape phase transitions in Cr isotopes with covariant density functional theory

Constrained relativistic mean field theory (RMF) has been employed for analysis of the shape phase transitions of even-even Cr52-66 isotopes. The systematic investigation of ground-state shape evolution between spherical U(5) and gamma-unstable O(6) for these nuclei has been carried out by using the potential energy curves (PECs) obtained from the effective interactions NL3*, TM1, PK1 and DD-ME2. The calculated PECs have indicated that Cr-58 can be a candidate for the critical-point nucleus with E(5) symmetry. A similar conclusion is also drawn from the calculated single-particle spectra of Cr-58 and is supported by the experimental data via observed ratios of the excitation energies. Furthermore, the gamma-independent character of Cr-58 has been pointed out by using its binding energy map in the beta-gamma plane obtained from the triaxial RMF calculations, in agreement with the condition of E(5) symmetry.