【学术视频】ASOS2019 | Gediminas Gaigalas of Vilnius University

更多精彩视频登陆网站

www.koushare.com

图 | Gediminas Gaigalas

题   目：Challenges of Theoretical Spectroscopy of Heavy Elements Towards Identification of Gravitational Wave Sources报告人：Gediminas Gaigalas单   位：Vilnius University时   间：2019-06-24地   点：复旦大学

扫码观看精彩报告视频

报告摘要

The detection of gravitational waves from mergers of neutron stars poses new tasks for contemporary theoretical atomic physics. Neutron stars mergers are so special system which consists mainly of r-process elements and in such system more than millions of weak transitions play important roles, and systematic atomic data are necessary. Therefore, it is essential to further develop ab initio methods allowing us to generate very accurate characteristics of atoms and ions, whose accuracy could compete or even exceed that of the experimental results.
In this presentation, the different methods, leading to the calculation scheme which allows us to perform the large scale theoretical studies of complex atoms and ions, are discussed. The approach is based on the multiconfiguration Dirack-Fock and relativistic configuration interaction methods in which for calculations of spin-angular parts of matrix elements the second quantization method in coupled tensorial form and quasispin technique were adopted. In case of complex electronic configurations, having several open shells, particularly open d- and f-shells, the main difficulties lie in calculations of the spin-angular parts of the relevant matrix elements of the operators considered. This phenomenon is even more pronounced if to extensively use the superposition of configurations methods, single and double excitations included. The use of the abovementioned second quantization and quasispin techniques, leading to triple tensors (in orbital, spin and quasispin spaces), enables us to efficiently overcome these difficulties and to achieve the breakthrough in the field, to essentially increase the efficacy and the speed of the calculations, opening the possibilities to consider extremely complex electronic configurations leading to the matrices of very large orders.
Non-relativistic and relativistic approaches as well as the accounting for quantum electrodynamics effects are considered. Various methods accounting for correlation effects are presented, too. The universal computer to calculate the matrix elements for electric and magnetic multipole transition operators, having not-specified value of the gauge condition of the electromagnetic field potential, are discussed. They allow us to study the general case of electronic transitions of any multipolarity.
A number of numerical results, obtained while using the above mentioned methods for heavy and super-heavy atoms as well as for ions, are presented and discussed as the examples. They demonstrate the practical possibilities of theoretical studies of complex ions, used for investigation of properties of kilonovae from dynamical and post-merger ejecta of neutron star mergers. 

个人简介

Gediminas Gaigalas, Chief Research Fellow at the Atomic Theory Department of the Vilnius University Research Institute of the Theoretical Physics and Astronomy and Head of the Chair at the General Physics Department of the Vilnius Pedagogical University. Graduated from Vilnius University in 1982. Doctor of natural sciences (Physics) 1989. Dr. Habil. of natural sciences (Physics) 2001. Field of the Research: Atomic Physics (Theoretical) 

会议简介

ASOS研讨会系1983年始办于瑞典隆德大学，随后每三年一届，在美国、荷兰、法国、加拿大、英国、比利时、巴西等多个国家的大学或科研机构举办。本着“将原子分子数据研究者与应用者凝聚在一起”的宗旨，一方面邀请研究原子结构与原子碰撞辐射特性相关课题的原子物理学家来介绍最新进展，另一方面邀请天体物理学家和实验室等离子体物理学家来综述他们最新关注的科学问题及其需要的原子数据。历经了36年的发展，逐步成为等离子体光谱领域具有国际影响力的盛会，成为该领域专家学者一个良好的学术交流与合作平台。第十三届研讨会在上海举行，由复旦大学主办。

—— ——往期精彩回顾—— ——

END

扫描二维码，关注微信公众号

戳这里，观看精彩视频哟！