The region of neutron-rich nuclei surrounding $N=28$ has garnered attention due to experimental and theoretical evidence indicating a diversity of shape and configuration coexistence. In the present Letter, we have performed a comprehensive study for these nuclei utilizing ab initio valence-space in-medium similarity renormalization group calculations with chiral nucleon-nucleon and three-nucleon interactions. First, the band structures of ${}^{41,43}\mathrm{S}$ and ${}^{45}\mathrm{Ar}$ are established via calculated spectra and $E2$ maps. The results well reproduce the $K=1/2$ ground state band and the $K=7/2$ band built upon the $7/2_1^{-}$ isomer in ${}^{43}\mathrm{S}$, which coexists with its $3/2_1^{-}$ ground state. Subsequently, the band structures of neutron-rich $N=27$ and $N=29$ isotones are discussed, with a focus on the potential emergence of configuration coexistence and isomers. We predict the presence of a similar configuration-coexisting $7/2_1^{-}$ isomeric state in ${}^{45}\mathrm{S}$, as an extension from ${}^{43}\mathrm{S}$. Furthermore, our calculations predict that the configuration-coexisting states also occur in the unbound ${}^{39}\mathrm{Mg}$ nucleus. Our ab initio calculations provide crucial insights into the collective structures of neutron-rich nuclei around $N=28$, specifically elucidating the phenomenon of configuration coexistence and isomers.

中文翻译：

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S45 中配置共存状态的从头计算：S43 的扩展

富中子核周围区域$氮=28$由于实验和理论证据表明形状和构型的多样性共存而引起了人们的关注。在本信中，我们利用手性核子-核子和三核子相互作用的从头算价空间介质内相似性重正化群计算对这些核进行了全面的研究。首先，能带结构${}^{41,43}\mathrm{S}$和${}^{45}\mathrm{氩气}$通过计算光谱建立$乙2$地图。结果很好地重现了$K=1/2$基态能带和$K=7/2$乐队建立在$7/2_1^{-}$异构体${}^{43}\mathrm{S}$，与其共存$3/2_1^{-}$基态。随后，富中子的能带结构$氮=27$和$氮=29$讨论了同位素，重点是构型共存和异构体的潜在出现。我们预测存在类似的共存配置$7/2_1^{-}$异构状态${}^{45}\mathrm{S}$，作为扩展${}^{43}\mathrm{S}$。此外，我们的计算预测构型共存状态也发生在未束缚中${}^{39}镁$核。我们的从头计算为了解周围富中子核的集体结构提供了重要的见解$氮=28$，具体阐明了构型共存和异构体的现象。