突破元素周期表超重元素挑战理论的极限

诸平

Fig. 1 Scientists from leading global institutions are advancing our understanding of the periodic table by exploring superheavy elements and the theoretical “island of stability.” Their research, highlighted in prestigious scientific publications, seeks to uncover the properties of elements with over 103 protons and to predict their behavior through theoretical models. This work promises to expand the boundaries of the periodic table and impact a range of scientific fields.

Fig. 2 Study graphic. Credit: Nature Reviews Physics February 2024, cover design Susanne Harris

Fig. 3 Credit: Physics Reports (2023). DOI: 10.1016/j.physrep.2023.09.004

据美国密歇根州立大学（Michigan State University）2024年3月31日提供的消息，突破元素周期表超重元素挑战理论的极限（Pushing the Limit of the Periodic Table – “Superheavy” Elements Challenge Theory）。来自新西兰梅西大学(Massey University in New Zealand)、德国美因茨大学（University of Mainz in Germany）、法国索邦大学（Sorbonne University in France）和稀有同位素束设施(Facility for Rare Isotope Beams简称FRIB)的科学家，讨论了元素周期表的极限，并根据超重元素研究的最新进展修改了“稳定岛”（“island of stability”）的概念。他们的研究成果登上了2024年2月刊《自然评论:物理学》（Nature Review Physics）的封面（Fig. 2）。详见：Odile R. Smits, Christoph E. Düllmann, Paul Indelicato, Witold Nazarewicz, Peter Schwerdtfeger. The quest for superheavy elements and the limit of the periodic table. Nature Reviews Physics. 2024, 6: 86–98. DOI: 10.1038/s42254-023-00668-y. Published: 11 December 2023. https://www.nature.com/articles/s42254-023-00668-y

参与此项研究的有来自新西兰理论化学与物理中心（Centre for Theoretical Chemistry and Physics, The New Zealand）、新西兰奥克兰梅西大学（Massey University Auckland, Auckland, New Zealand）、德国美因茨的约翰内斯·古腾堡大学（Johannes Gutenberg University Mainz, Mainz, Germany）、德国达姆施塔特的GSI亥姆霍兹重离子研究中心有限公司（GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany）、德国美因茨亥姆霍兹研究所（Helmholtz Institute Mainz, Mainz, Germany）、法国索邦大学、法国国家科学研究院、法国高等教育学院、法兰西学院共同运营的卡斯特勒·布罗塞尔实验室（Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, Paris, France）、美国密歇根州立大学（Michigan State University, East Lansing, MI, USA）的研究人员。

除了《自然评论:物理学》（Nature Reviews Physics）外，《物理报告》（Physics Reports）还发表了一篇关于超重元素原子电子结构理论的综述。详见：O.R. Smits(Auckland U.), P. Indelicato(Paris, Lab. Kastler Brossel), W. Nazarewicz(Michigan State U., East Lansing (main)), M. Piibeleht(Auckland U.), P. Schwerdtfeger(Auckland U.). Pushing the limits of the periodic table — A review on atomic relativistic electronic structure theory and calculations for the superheavy elements. Physics Reports, 2023, 1035: 1-57. DOI: 10.1016/j.physrep.2023.09.004. Pub Date: September 2023.

寻找超重元素（The Quest for Superheavy Elements）

何为最重的束缚原子核和最重的束缚原子?它们的性质如何?质子数超过103个的原子核被标记为超重元素。它们是科学家们试图揭开的这些核的广阔未知领域的一部分。探索这一未知领域为连接广泛科学领域的发现提供了前景。新的实验设施正在建设中，以帮助科学家揭示原子及其原子核在大量电子、质子和中子的状态下的特性。这些设施将在原子序数和质量的限制下创造新的元素和核素。

超重核的生成速率极低。从这些实验中获得的物理和化学数据表明了与较轻元素和同位素的偏差。这使得科学家们可以质疑元素周期表（Periodic Table of the Elements）和核素表（Chart of the Nuclides）的边界可以扩大多少。评估延长稳定半岛（“peninsula of extended stability”）的存在也是一个科学目标，在那里，超重核的寿命可能超过目前发现的寿命极短的核。

此外，原子结构理论的进展主要集中在超重元素及其预测的电子基态构型上，这对元素在元素周期表中的位置很重要。

超重元素的理论进展与未来（Theoretical Advances and the Future of Superheavy Elements）

该论文的作者之一、约翰·汉娜杰出物理学教授（John A. Hannah Distinguished Professor of Physics）、稀有同位素束设施(FRIB)的首席科学家维特克·纳扎雷维奇（Witek Nazarewicz）说:“由于存在巨大的静电力，超重原子中的电子以接近光速的速度运动。此外，超重核中非常强的库仑力会产生新的效应。这是原子和核理论的新局面。”

在FRIB，科学家们将研究如何到达更靠近增强稳定性区域的超重核。许多超重核目前无法测量，因此关于它们的信息必须来自理论推断。FRIB的核理论家利用高性能计算和机器学习辅助的先进模型对超重核进行预测。研究元素周期表和超重区的核景观（nuclear landscape）将产生会影响核物理和原子物理、天体物理学和化学的新思想和方法。

本研究得到了休伯特·居里·杜蒙·居维尔计划新西兰-法国科技支援计划（Program Hubert Curien Dumont d’Urville New Zealand - France Science & Technology Support Program number 43245QC）、新西兰皇家学会马斯登基金（Marsden Fund of the Royal Society of New Zealand）以及美国能源部{US Department of Energy under Award Numbers DOE-DE-NA0004074 (NNSA, the Stewardship Science Academic Alliances program) and DE-SC0013365 and DE-SC0023175 (Office of Science, Office of Nuclear Physics)}的资助。

上述介绍，仅供参考。欲了解更多信息，敬请注意浏览原文或者相关报道。

Pushing the limit of the periodic table with superheavy elements (2024, March 19; retrieved 2 April 2024)

Abstract (DOI: 10.1038/s42254-023-00668-y)

The borders of the periodic table of the elements and of the chart of nuclides are not set in stone. The desire to explore the properties of atoms and their nuclei in a regime of very large numbers of electrons, protons and neutrons has motivated new experimental facilities to create new elements and nuclides at the limits of atomic number and mass. But the small production rates and short lifetimes of superheavy nuclei and their atoms mean that ‘atom-at-a-time’ studies are the only experimental way to probe them. The physical and chemical data obtained so far, augmented by theoretical calculations, indicate significant deviations from extrapolations from lighter elements and isotopes. This situation raises the following question: how much further can one push the limits of the periodic table? In this Review, we describe the major challenges in the field of the superheavy elements and speculate about future directions.

Abstract（DOI: 10.1016/j.physrep.2023.09.004）

We review the progress in atomic structure theory with a focus on superheavy elements and their predicted ground state configurations important for an element's placement in the periodic table. To understand the electronic structure and correlations in the regime of large atomic numbers, it is essential to correctly solve the Dirac equation in strong Coulomb fields, and to take into account quantum electrodynamic effects. We specifically focus on the fundamental difficulties encountered when dealing with the many-particle Dirac equation. We further discuss the possibility for future many-electron atomic structure calculations going beyond the critical nuclear charge Z_crit ≈ 170 , where levels such as the 1 s shell dive into the negative energy continuum (E_nκ < -m_ec²). The nature of the resulting Gamow states within a rigged Hilbert space formalism is highlighted.