<p>Neutron-rich boron, carbon, and nitrogen isotopes have garnered extensive experimental and theoretical interest. In the present work, we conducted a comprehensive study of these nuclei by utilizing <i>ab initio</i> valence-space in-medium similarity renormalization group calculations with chiral nucleon–nucleon and three-nucleon interactions. First, we systematically calculated the spectra of nuclei. Our results align well with the available experimental data, which are comparable to phenomenological shell model calculations. Subsequently, the evolution of the <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1796_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">$N=14$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>N</mi> <mo>=</mo> <mn>14</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1796_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">$N=16$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>N</mi> <mo>=</mo> <mn>16</mn> </mrow> </math></EquationSource> </InlineEquation> shell gaps is discussed based on the calculated spectra and the effective single-particle energies. Our calculations suggest that the <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1796_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">$N=14$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>N</mi> <mo>=</mo> <mn>14</mn> </mrow> </math></EquationSource> </InlineEquation> neutron subshell is present in the oxygen isotopes but disappears in the boron, carbon, and nitrogen isotopic chains. Moreover, the <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1796_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">$N=16$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>N</mi> <mo>=</mo> <mn>16</mn> </mrow> </math></EquationSource> </InlineEquation> subshell is present in all isotopes but gradually decreases from <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1796_Article_IEq5.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">$^{24}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>24</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>O to <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1796_Article_IEq6.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">$^{21}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>21</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>B. These results provide valuable information for future studies.</p>

Study of shell evolution in neutron-rich boron, carbon, and nitrogen isotopes with in-medium similarity renormalization group calculations

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发表日期：

2025年9月12日

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Liu-Yuan Shen,
Qi Yuan,
Hong-Hui Li,
Meng-Ran Xie,
Jian-Guo Li,
Wei Zuo

摘要

Neutron-rich boron, carbon, and nitrogen isotopes have garnered extensive experimental and theoretical interest. In the present work, we conducted a comprehensive study of these nuclei by utilizing ab initio valence-space in-medium similarity renormalization group calculations with chiral nucleon–nucleon and three-nucleon interactions. First, we systematically calculated the spectra of nuclei. Our results align well with the available experimental data, which are comparable to phenomenological shell model calculations. Subsequently, the evolution of the $N=14$ $N = 14$ and $N=16$ $N = 16$ shell gaps is discussed based on the calculated spectra and the effective single-particle energies. Our calculations suggest that the $N=14$ $N = 14$ neutron subshell is present in the oxygen isotopes but disappears in the boron, carbon, and nitrogen isotopic chains. Moreover, the $N=16$ $N = 16$ subshell is present in all isotopes but gradually decreases from $^{24}$ $^{24}$ O to $^{21}$ $^{21}$ B. These results provide valuable information for future studies.