Dipole excitation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Li</mml:mi><mml:mprescripts/><mml:none/><mml:mn>6</mml:mn></mml:mmultiscripts></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Be</mml:mi><mml:mprescripts/><mml:none/><mml:mn>9</mml:mn></mml:mmultiscripts></mml:math> studied with an extended quantum molecular dynamics model
B. Huang, Y. G.
Abstract
The $\ensuremath{\alpha}$ ($^{4}\mathrm{He}$)-clustering structure is a common phenomenon in light nuclei due to the decreasing contribution of the mean field in few-body systems. In this work, we presented calculations of giant dipole resonance (GDR) excitations for two non-$\ensuremath{\alpha}$-conjugate light nuclei, namely $^{6}\mathrm{Li}$ and $^{9}\mathrm{Be}$, within a framework of an extended quantum molecular dynamics model. For $^{6}\mathrm{Li}$, we investigated the GDR spectra from the two-body clustering structure with $\ensuremath{\alpha}\phantom{\rule{4pt}{0ex}}+$ deuteron as well as the three-body structure with $\ensuremath{\alpha}+n+p$, and found that the major $\ensuremath{\alpha}$-clustering contribution on the GDR peak is located at around 31 MeV, while the resonance contributions between clusters, namely $\ensuremath{\alpha}$ and deuteron or $(n+p)$, are located on the lower energy side, which can be regarded as the pygmy dipole resonance (PDR). For $^{9}\mathrm{Be}$, a mixture configuration contribution for the chain-like structure and Borromean-like structure of the $\ensuremath{\alpha}\phantom{\rule{4pt}{0ex}}+\phantom{\rule{4pt}{0ex}}n\phantom{\rule{4pt}{0ex}}+\phantom{\rule{4pt}{0ex}}\ensuremath{\alpha}$ configuration can explain its GDR results.