发表机构
Université libre de Bruxelles; KU Leuven（布鲁塞尔自由大学; 荷语鲁汶大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种基于二维贪心策略的降阶建模方法，以20倍加速模拟FAM-QRPA核响应计算，并发现BSk(G)泛函下Pb-208的ISGMR质心与核物质不可压缩性无相关性。
AI 中文摘要
线性响应理论提供了关于多体系统（如原子核）激发的重要信息。它给出基态跃迁概率或强度函数，由此可以推导出反应速率和截面。这些量例如是天体物理模拟和β衰变建模的关键输入。目前，模拟全局核性质最普遍的理论框架是能量密度泛函（EDF）理论。现代线性响应方法在平均场真空之上采用准粒子随机相位近似（QRPA）。这可以通过使用传统的矩阵QRPA公式来实现，但使用有限振幅方法（FAM）可以大幅加速。然而，在整个核素图上获得高分辨率的响应函数在计算上仍然要求很高，这限制了大规模应用。本工作引入了一种降阶建模（ROM）方法来模拟有限振幅方法（FAM-QRPA）计算，显著降低了获得核响应函数的计算成本。通过采用二维贪心策略从一小部分快照进行插值，该仿真器实现了20倍的加速，同时在不同核、算符和能量密度泛函（EDF）上保持高精度。本工作的第二个目标是研究无限核物质不可压缩性与Pb-208的ISGMR质心位置之间的相关性，特别是针对在布鲁塞尔开发的EDF形式和参数化：BSk(G)族。我们的结果表明，这种相关性并不持续存在。
英文摘要
Linear response theory provides essential information regarding the excitations of many-body systems, such as atomic nuclei. It yields ground state transition probabilities, or strength functions, from which reaction rates and cross-sections can be derived. These quantities are for example a critical input for astrophysical simulations and modelling of beta-decay. Currently, the most general theoretical framework for modelling global nuclear properties is Energy Density Functional (EDF) theory. Modern approaches for linear response employ the quasiparticle random-phase approximation (QRPA) on top of a mean-field vacuum. This can be done by using conventional matrix QRPA formulations, but can be sped up substantially by using the finite amplitude method (FAM). Nevertheless, obtaining highly-resolved response functions over the complete nuclear chart remains computationally demanding, which limits large-scale applications. This work introduces a Reduced Order Modeling (ROM) approach to emulate Finite Amplitude Method (FAM-QRPA) calculations, significantly reducing the computational cost of obtaining nuclear response functions. By employing a 2D-greedy strategy to interpolate from a small set of snapshots, the emulator achieves a x20 speed-up while maintaining high accuracy across various nuclei, operators, and energy density functionals (EDFs). A second objective of this work is to investigate the correlation between the infinite nuclear matter incompressibility and the ISGMR centroid position of Pb-208, specifically for EDF forms and parametrisations developed in Brussels: the BSk(G)-family. Our results indicate that the correlation does not persist.
CommentsDissertation presented in fulfillment of the requirements for the degree of Master of Physics. Supervised by Dr. W. Ryssens. Corrected version containing minor corrections to the original (https://lib.is/lbsn9994932375301471)
