Systematic study of surface properties for Ne, Na, Mg, Al and Si isotopes in a coherent density fluctuation model using the relativistic mean field formalism

TL;DR

This study systematically investigates surface properties of certain isotopes using a relativistic mean-field approach combined with the coherent density fluctuation model, revealing irregular trends in symmetry energy for light nuclei.

Contribution

It applies the CDFM with relativistic mean-field densities to analyze surface properties and symmetry energy decomposition in isotopes, highlighting irregular behaviors in light nuclei.

Findings

Large symmetric energies observed for isotopes in the island of inversion.

Irregular trend in symmetry energy across the studied isotopic chain.

Discussion on possible reasons for abnormal symmetry energy behavior.

Abstract

We have systematically studied the surface properties, such as symmetric energy, neutron pressure, and symmetry energy curvature coefficient for Ne, Na, Mg, Al, and Si nuclei from the proton to neutron drip-lines. The Coherent Density Fluctuation Model (CDFM) is used to estimate these quantities taking the relativistic mean-field densities as inputs. The Br\"uckner energy density functional is taken for the nuclear matter binding energy and local density approximation is applied for its conversion to coordinate space. The symmetry energy again decomposed to the volume and surface components within the liquid drop model formalism to the volume and surface parts separately. Before calculating the surface properties of finite nuclei, the calculated bulk properties are compared with the experimental data, whenever available. The NL3* parameter set with the BCS pairing approach in an axially deformed frame-work is used to take care of the pairing correlation when needed. The deformed density is converted to its spherical equivalent with a two Gaussian fitting, which is used as an input for the calculation of weight function in the CDFM approximation. With the help of the symmetric energy for the recently isotopes $^{29}$F, $^{28}$Ne, $^{29,30}$Na and $^{31,35,36}$Mg are considered to be within the {\it island of inversion} emphasized {\bf [Phys. Lett. B 772, 529 (2017)]}. Although we get large symmetric energies corresponding to a few neutron numbers for this isotopic chain as expected, an irregular trend appears for all these considered nuclei. The possible reason behind this abnormal behavior of symmetry energy for these lighter mass nuclei is also included in the discussion, which gives a direction for future analysis.