Density-driven α-particle clustering in neutron-rich oxygen isotopes
Abstract
In this work, we study the effect of valence neutrons on density-driven localisation in the neutron-rich oxygen isotopes. Calculations are performed within the multidimensionally constrained relativistic Hartree--Bogoliubov model using the DD-ME2 covariant energy-density functional. By constraining the mass rms radius to larger values, we study the structural evolution of these nuclei under progressive dilution, from spatially delocalised configurations to localised clustered states. The total energy, pairing correlations, deformation, and proton and neutron density distributions are analysed to determine how valence neutrons influence the emergence of α-like clustering. For all three isotopes, we find a transition from a spatially delocalised nucleonic configuration to a tetrahedral 4α-like structure. The onset of this transition occurs at similar values of the radius-derived relative dilution parameter, χPT=ρPT/ ρGS≃ 0.28--$0.31$, and shows only a weak dependence on neutron number. The excess neutrons modify the clustered density by increasing the density in the central regions and between clusters, while leaving the underlying tetrahedral core structure largely intact. Finally, we also use a phenomenological four-centre Hückel-type mapping of nuclei, which provides a molecular-orbital-like interpretation of cluster structures. We find that the effective coupling between the cluster centers decreases by progressively expanding the nucleus. The centroid-referenced energy shift ΔEval also becomes less negative and provides smaller net molecular-orbital-like energy lowering relative to its centroid with increasing neutron number.
Versions
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BibTeX
@misc{davies2026densitydriven,
title = {{Density-driven $α$-particle clustering in neutron-rich oxygen isotopes}},
author = {M. Davies and E. Yüksel and J. -P. Ebran and E. Khan},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.06883},
eprint = {2611.06883},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.06883},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Density-driven α-particle clustering in neutron-rich oxygen isotopes
AU - M. Davies
AU - E. Yüksel
AU - J. -P. Ebran
AU - E. Khan
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.06883
UR - https://arxiv.org/abs/2611.06883
AB - In this work, we study the effect of valence neutrons on density-driven localisation in the neutron-rich oxygen isotopes. Calculations are performed within the multidimensionally constrained relativistic Hartree--Bogoliubov model using the DD-ME2 covariant energy-density functional. By constraining the mass rms radius to larger values, we study the structural evolution of these nuclei under progressive dilution, from spatially delocalised configurations to localised clustered states. The total energy, pairing correlations, deformation, and proton and neutron density distributions are analysed to determine how valence neutrons influence the emergence of α-like clustering. For all three isotopes, we find a transition from a spatially delocalised nucleonic configuration to a tetrahedral 4α-like structure. The onset of this transition occurs at similar values of the radius-derived relative dilution parameter, χ_PT=ρ_PT/ ρ_GS≃ 0.28--$0.31$, and shows only a weak dependence on neutron number. The excess neutrons modify the clustered density by increasing the density in the central regions and between clusters, while leaving the underlying tetrahedral core structure largely intact. Finally, we also use a phenomenological four-centre Hückel-type mapping of nuclei, which provides a molecular-orbital-like interpretation of cluster structures. We find that the effective coupling between the cluster centers decreases by progressively expanding the nucleus. The centroid-referenced energy shift ΔE_val also becomes less negative and provides smaller net molecular-orbital-like energy lowering relative to its centroid with increasing neutron number.
ER -