Nuclear response theory with multiphonon coupling in a covariant framework
Nuclear response theory with multiphonon coupling in a covariant framework
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协变框架中多声子耦合的核反应理论
DOI：
10.1103/physrevc.91.034332
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发表时间：
2014
影响因子：
3.1
通讯作者：
E. Litvinova
中科院分区：
文献类型：
--
作者：
E. Litvinova
背景：在很大的激发能范围内，核激发态都是用线性响应理论来描述的。除了在准粒子随机位相近似(QRPA)中将激发态表示为两个关联的准粒子(2q)之外，还存在对4q组态的扩展。这种扩展的方法在描述核谱的总体性质方面是相当成功的，然而，考虑到它们的许多精细特征，需要进一步扩展组态空间。目的：这项工作旨在开发一种方法，能够进行这种扩展，并能够再现和预测在低能量下特别感兴趣的精细光谱性质。方法：基于协变密度泛函理论和时间块近似，将其推广到准粒子和多声子激发之间的耦合。结果：发展了协变多声子响应理论，并将其应用于中等质量和重质量核的结构计算。该方程在球基上既有一般形式又有耦合形式。结论：发展的协变多声子响应理论代表了核响应的新一代方法，旨在统一描述中等质量和重质量核的高频集体态和低能谱。
Background: Nuclear excited states within a wide range of excitation energies are formally described by the linear response theory. Besides its conventional formulation within the quasiparticle random phase approximation (QRPA) representing excited states as two correlated quasiparticles (2q), there exist extensions for 4q configurations. Such extended approaches are quite successful in the description of gross properties of nuclear spectra, however, accounting for many of their fine features requires further extension of the configuration space. Purpose: This work aims at the development of an approach which is capable of such an extension as well as of reproducing and predicting fine spectral properties, which are of special interest at low energies. Method: The method is based on the covariant density functional theory and time blocking approximation, which is extended for couplings between quasiparticles and multiphonon excitations. Results: The covariant multiphonon response theory is developed and adopted for nuclear structure calculations in medium-mass and heavy nuclei. The equations are formulated in both general and coupled forms in the spherical basis. Conclusions: The developed covariant multiphonon response theory represents a new generation of the approaches to nuclear response, which aims at a unified description of both high-frequency collective states and low-energy spectroscopy in medium-mass and heavy nuclei.