科研之友
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摘要
Background: Nuclear excited states within a wide range of excitation energies are formally described by linear response theory. Besides its conventional formulation within the quasiparticle random phase approximation representing excited states as two correlated quasiparticles, there exist extensions for four-quasiparticle 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. <br xmlns:set="http://exslt.org/sets">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 covariant density functional theory and the time-blocking approximation, which is extended for couplings between quasiparticles and multiphonon excitations. Results: A 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 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.
- 出版日期2015-3-26
