Large quadrupole moment in ²⁰Ne: Localization and tensor-force effects

Using the beyond-Skyrme-Hartree-Fock approach with various Skyrme-type NN effective interactions, we explore the large spectroscopic quadrupole moment Q_s of the first excited 2₁ ⁺ state in ²⁰Ne. Our calculated Q_s(2₁ ⁺) ≈ −0.20 eb aligns closely with the experimental value of −0.22(2) eb. Consistent with other theoretical methods, our results confirm the presence of an α cluster structure in this state. We also investigate the robustness of the α cluster against tensor force, demonstrating that incorporating tensor components significantly enhances Q_s(2₁ ⁺) and strengthens the cluster structure along the symmetrical axis.