Multi-dimensional potential energy surfaces and non-axial octupole correlations in actinide and transfermium nuclei from relativistic mean field models

We have developed multi-dimensional constrained covariant density functional theories (MDC-CDFT) for finite nuclei in which the shape degrees of freedom beta(lambda mu), with even mu, e.g., beta(20), beta(22), beta(30), beta(32), beta(40), etc., can be described simultaneously. The functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. For the pp channel, either the BCS approach or the Bogoliubov transformation is implemented. The MDC-CDFTs with the BCS approach for the pairing (in the following labelled as MDC-RMF models with RMF standing for relativistic mean field) have been applied to investigate multi-dimensional potential energy surfaces and the non-axial octupole Y-32-correlations in N = 150 isotones. In this contribution we present briefly the formalism of MDC-RMF models and some results from these models. The potential energy surfaces with and without triaxial deformations are compared and it is found that the triaxiality plays an important role upon the second fission barriers of actinide nuclei. In the study of Y-32-correlations in N = 150 isotones, it is found that, for Cf-248 and Fm-250, beta(32) > 0.03 and the energy is lowered by the beta(32) distortion by more than 300 keV; while for Cm-246 and No-252, the pocket with respect to beta(32) is quite shallow.