Bing-Nan Lu, Jie Zhao, En-Guang Zhao, Shan-Gui Zhou
By breaking the reflection and the axial symmetries simultaneously, we developed multi-dimensional constraint relativistic mean field (MDC-RMF) models. In these models, the nuclear shape is assumed to be invariant under the reversion of x and y axes, i.e., the intrinsic symmetry group is V_4 and all shape degrees of freedom \beta_{\lambda\mu} with even \mu (\beta_{20}, \beta_{22}, \beta_{30}, \beta_{32}, \beta_{40}, ...) are included self-consistently. The RMF 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. The pairing effects are taken into account with the BCS approach. In this paper the formalism for MDC-RMF models is presented in details. Potential energy surface of 240Pu is illustrated for numerical checks and for the study of the effects of triaxiality on the fission barriers. Potential energy curves of actinide nuclei around the first and second fission barriers are studied systematically with emphasis on the second ones which are lowered considerably by the triaxial deformation. We conclude that it is important to include the reflection asymmetric and non-axial shapes simultaneously for the study of potential energy surfaces and fission barriers of actinide nuclei and of those in unknown mass regions such as superheavy nuclei.
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http://arxiv.org/abs/1304.2513
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