原子核链式α结团结构及其动力学的协变密度泛函理论研究

Structure and dynamics of linear-chain α cluster in covariant density functional theory

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中文摘要：本文回顾了基于协变密度泛函理论研究原子核链式α结团结构及其动力学的现状.协变密度泛函理论以核子为基本自由度,可以自洽地给出具有α结团现象的原子核链式结团结构.结合推转平均场方法,相关研究揭示了碳同位素链式结团结构中自旋和同位旋的相干效应.随着转动频率的增加,中子的σ轨道(平行于对称轴的轨道)的能量在科氏力作用下降低,进而被价中子占据,预示着链式结构更容易在丰中子原子核的高角动量态中发现.类似的现象同样出现在丰质子的3α和4α链式结团结构中,并且价质子能在更低的角动量下占据质子的σ轨道.三维格点空间的协变密度泛函理论研究表明:转动频率在2.0-3.5MeV区间内,12C中的链式结团结构是位能面上的极小,表现出对弯曲运动和裂变的稳定性.进一步,含时协变密度泛函理论给出了4He+8Be和4He+10Be共振散射形成12C和14C链式结团结构的动力学过程,并发现价中子的动力学同位旋效应减缓了结团的纵向振荡,使得形成的14C链式结团结构有更长的寿命.

外文摘要：Recent progress in the structure and dynamics of nuclear linear-chain α clusters within the framework of covariant density functional theory is reviewed.The covariant density functional theory does not a priori assume the existence of α clusters and provides a microscopic and self-consistent description of the corresponding linear-chain cluster structure.By combin-ing the covariant density functional theory with the cranking model,the coherent effects of nuclear spin and isospin on the linear-chain cluster structure of carbon isotopes are revealed.Owing to the effects of the Coriolis term in the cranking covariant density functional theory,σ orbitals show a reduction in energy with the rotational frequency and are occupied by valence neutrons,indicating that the linear-chain cluster structures are more feasible in fast-rotating neutron-rich nu-clei.A similar mechanism exists for the 3a and 4α linear-chain cluster structures in proton-rich nuclei,wherein protons occupy σ orbitals at lower angular momenta than those observed for neutrons.Based on the calculations of the covari-ant density functional theory in a three-dimensional lattice space,the linear-chain cluster configuration in 12C is shown as a state with the minimum energy on the potential energy surface for rotational frequencies of 2.0-3.5 MeV,thereby demonstrating the stability of the linear-chain cluster structure against nuclear bending motion and fission.Furthermore,the development of the time-dependent covariant density functional theory enables the dynamical study of the linear-chain cluster structure.Investigations of the microscopic dynamics of the linear-chain cluster states for 12C and 14C isotopes in the reactions 4He+8Be and 4He+10Be show that the dynamical isospin effects by the valence neutrons impede the longitudinal oscillations of clusters,thereby prolonging the lifetime of the linear-chain cluster states.

外文关键词：

covariant density functional theorynuclear clusterslinear chain cluster structurenuclear rotationresonance scattering

作者：

张丹丹、任政学、赵鹏巍

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作者单位：

北京大学物理学院,核物理与核技术国家重点实验室,北京 100871

于利希研究中心,原子核物理所和高等计算所,于利希D-52425,德国

波恩大学,亥姆霍兹辐射与核物理研究所,波恩D-53115,德国

关键词：

协变密度泛函理论原子核结团链式结团结构原子核转动共振散射

基金：

国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金北京大学核物理与核技术国家重点实验室科技部高端外国专家引进计划北京大学高性能计算平台资助项目

项目编号：

11935003119750311207013100112141501NPT2020ZZ01

出版年：

2024

DOI：

10.1360/SSPMA-2023-0458

中国科学(物理学力学天文学)

中国科学院

中国科学(物理学力学天文学)

CSTPCD北大核心

影响因子：0.644

ISSN：1674-7275

年,卷(期)：2024.54(9)