Papers
Topics
Authors
Recent
Gemini 2.5 Flash
Gemini 2.5 Flash
117 tokens/sec
GPT-4o
8 tokens/sec
Gemini 2.5 Pro Pro
47 tokens/sec
o3 Pro
5 tokens/sec
GPT-4.1 Pro
38 tokens/sec
DeepSeek R1 via Azure Pro
28 tokens/sec
2000 character limit reached

Nuclear energy density optimization: Large deformations (1111.4344v2)

Published 18 Nov 2011 in nucl-th

Abstract: A new Skyrme-like energy density suitable for studies of strongly elongated nuclei has been determined in the framework of the Hartree-Fock-Bogoliubov theory using the recently developed model-based, derivative-free optimization algorithm POUNDerS. A sensitivity analysis at the optimal solution has revealed the importance of states at large deformations in driving the parameterization of the functional. The good agreement with experimental data on masses and separation energies, achieved with the previous parameterization UNEDF0, is largely preserved. In addition, the new energy density UNEDF1 gives a much improved description of the fission barriers in 240Pu and neighboring nuclei.

Citations (247)

Summary

  • The paper presents a new Skyrme-like parameterization, UNEDF1, optimized using a derivative-free algorithm to enhance fission barrier predictions for deformed nuclei.
  • It conducts a detailed sensitivity analysis that reveals strong correlations among parameters like effective mass and pairing strengths.
  • The research achieves high numerical precision in modeling large amplitude collective motions, outperforming prior EDF parameterizations in fission studies.

Nuclear Energy Density Optimization: Large Deformations

This paper presents an extensive paper on optimizing nuclear energy density functions to better describe strongly deformed nuclei, emphasizing applications in fission calculations. The research develops a new Skyrme-like parameterization, termed UNEDF1, within the framework of the Hartree-Fock-Bogoliubov (HFB) approach. The authors apply a model-based, derivative-free optimization algorithm known as POUND to precisely calibrate the parameters of the energy density functional (EDF) to both traditional nuclear data and new constraints from strongly deformed nuclei states.

Key Findings and Numerical Insights

  • Optimization of EDF Parameters: The optimization task focuses on refining the description of fission isomers in actinides, notably improving upon the fission barrier predictions. The paper reports that the new configuration (UNEDF1) extends the previous parameterization UNEDF0 by improving the description of these large deformation features.
  • Parameter Sensitivity and Correlation: A detailed sensitivity analysis evaluates the impact of each data point on the model parameters. Strong correlations among certain parameters, such as between the effective mass and pairing strengths, are highlighted, pointing to complex interdependencies that must be considered in future refinements.
  • Numerical Precision: Through extensive computational simulations, utilizing high-performance computing facilities, UNEDF1 has been systematically optimized for accuracy in describing large amplitude collective motions. This was achieved by accounting explicitly for extensive deformations in the dataset, thereby enhancing the model's applicability in predicting fission and fusion phenomena.
  • Comparative Performance: UNEDF1 shows significant improvements in predicting experimental fission barrier heights for the actinides compared to the previous parameter set and other models. This improvement strongly supports the hypothesis that incorporating data on large deformations into the optimization process yields a more accurate EDF for fission studies.

Theoretical and Practical Implications

The development of UNEDF1 marks a significant step forward in nuclear structure theory, particularly in the context of EDF modeling. The work underscores the critical need to optimize EDF parameters against a broad range of observables, including those at large deformations, to achieve an energetically accurate functional. Practically, this approach can vastly improve theoretical predictions for nuclear processes like fission, crucial for applications in nuclear energy and understanding fundamental nuclear physics.

Future Developments

The research opens several pathways for further paper. The authors suggest that including neutron-rich systems (e.g., neutron drops) and spin-orbit data in future optimizations could provide a more comprehensive EDF for diverse nuclear systems. Another promising direction involves enhancing the description of pairing correlations and tackling the challenges of symmetry breaking, which remain pivotal for extending the utility and accuracy of nuclear EDFs in theoretical nuclear physics.

Overall, this paper contributes significantly to the methodology of constructing and optimizing nuclear energy density functionals, pushing the precision frontier in modeling complex nuclear phenomena, particularly large-deformation processes like fission.