Unified mechanism behind the even-parity ground state and neutron halo of ¹¹Be*

Using the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model, we explore mechanism behind parity inversion and halo occurrence in $^{11}$Be, which are well reproduced by RHF Lagrangian PKA1. It is illustrated that evidently enhanced deformation effects $\pi$-pseudo-vector $\rho$-tensor couplings PKA1 crucial for correctly describing both even-parity ground state (GS) neutron of $^{11}$Be. Coupling with deformation, intrude $1d_{5/2}$ component largely enhances between orbit $1/2_2^+$ nuclear core to promise GS, whereas $2s_{1/2}$ therein dominates formation Moreover, $^{11}$Be found be stabilized attractive inherent correlations components $1/2_2^+$, instead pairing correlations, paves a new way understand pictures unstable nuclei.