Effects of rotation and valence nucleons in molecular-like ${\alpha}$-chain nuclei

TL;DR

This study uses a covariant density functional theory-based lattice cranking model to analyze how rotation influences valence nucleon orbitals and stabilizes linear alpha-chain structures in certain nuclei, revealing orbital transitions at specific rotational frequencies.

Contribution

It introduces a three-dimensional lattice cranking model to investigate valence nucleon orbital transitions and structural stability in alpha-chain nuclei under rotation.

Findings

Valence protons in $^{16}$Ne transition from $ ext{pi}$ to $ ext{sigma}$ orbital at ~1.3 MeV rotational frequency.

Valence neutrons in $^{16}$C transition at a higher frequency (~1.7 MeV).

Valence proton effects are similar in $^{20}$Mg compared to neutrons in $^{20}$O.

Abstract

Effects of rotation and valence nucleons in molecular-like linear $\alpha$-chain nuclei are analyzed using a three-dimensional lattice cranking model based on covariant density functional theory. The structure of $^{16}$C and $^{16}$Ne is investigated as a function of rotational frequency. The valence nucleons, with respect to the 3$\alpha$ linear chain core of $^{12}$C, at low frequency occupy the $\pi$ molecular orbital. With increasing rotational frequency these nucleons transition from the $\pi$ orbital to the $\sigma$ molecular orbital, thus stabilizing the 3$\alpha$ linear chain structure. It is predicted that the valence protons in $^{16}$Ne change occupation from the $\pi$ to the $\sigma$ molecular orbital at $\hbar\omega \approx 1.3$ MeV, a lower rotational frequency compared to $\hbar\omega \approx 1.7$ MeV for the valence neutrons in $^{16}$C. The same effects of valence protons are found in $^{20}$Mg, compared to the four valence neutrons in $^{20}$O. The model is also used to examine the effect of alignment of valence nucleons on the relative positions and size of the three $\alpha$-clusters in $^{16}$C and $^{16}$Ne.