Analysis of the effect of core structure upon dineutron correlation using antisymmetrized molecular dynamics

Abstract

We extend the method of antisymmetrized molecular dynamics (AMD) to investigate dineutron correlation. We regard the total system as the core plus two valence neutrons in the AMD framework and treat the valence neutron wave functions by multirange Gaussians with the $d$-constraint method, in which the distance between the core and the center of mass of the two neutrons is constrained, to describe the size changing effect and the motion of two neutrons. We apply this method to the ground state of $^{10}\mathrm{Be}$ as an example and investigate the motion of two neutrons around a largely deformed $^{8}\mathrm{Be}$ core by analyzing the two-neutron overlap function around the core. Comparing the results including the different $^{8}\mathrm{Be}$ core structures, we show that the core structure plays an important role in dineutron formation and expansion from the core. The radial fluctuation in the core leads to the expansion of the core potential to the farther region and, as a result, two valence neutrons can be expanded far from the core to form a dineutron. Differently, when the core is less deformed, the dineutron is dissociated by the spin-orbit potential at the surface of the core. We can investigate the dineutron correlation clearly by using the present framework and conclude that the framework is effective for the studies of dineutron correlation.