The international collaboration on Computation Atomic Structure

Tribute to Charlotte Froese Fischer and Ian Philip Grant

With deep sadness, we inform the scientific community that the two leaders of the Computation Atomic Structure Collaboration passed away one year apart: Charlotte Froese Fischer passed away on February 8, 2024. Ian Philip Grant passed away on March 1, 2025. Charlotte and Ian supervised, advised, and collaborated with many students, postdocs, and other collaborators, including several members of the Computational Atomic Structure (CompAS) Collaboration. They both were the founding members and natural leaders of the CompAS Collaboration. They initiated, coordinated, and advised many joint projects, most importantly the projects related/involving the development of computer codes for the study of atomic properties. They have been the inspiration for so many young scientists. Charlotte and Ian will be dearly missed by all of us.

News!

The next CompAS meeting will be held in Nice, France in July 2026.

Welcome!

To meet the demands for atomic data in the Computational Atomic Structure (CompAS) group has been formed. The collaboration is involved in developing state of the art computer codes for atomic calculations in the non-relativistic scheme with relativistic corrections in the Breit-Pauli approximation ATSP2K as well as in the fully relativistic scheme GRASP2018. The codes rely on multiconfiguration methods and the wave function for an atomic state is expanded in configuration state functions (CSFs).

Moreover, the RATIP program supports the calculation of atomic properties for open-shell atoms with one electron in the continuum, including transition probabilities, Auger parameters as well as a variety of excitation, ionization and recombination amplitudes and cross sections.

In addition to the code development itself, the group includes members with expertise in the methods and is constantly developing computational techniques for the evaluation of atomic properties of the highest quality.

The year 2022 not only marks the 10th anniversary of Atoms, but also the 10th anniversary of the CompAS group. A Special Issue of Atoms entitled “The General Relativistic Atomic Structure Package - GRASP”, celebrates both these milestones by presenting the General Relativistic Atomic Structure Program (GRASP), its underlying theory, computational procedures, and benchmark results. A GRASP manual to assist the application of the codes to atomic physics and promote the future development of the code are included.

The CompAS remits (definition, board, membership, terms of collaboration, core members, etc) can be found in ???

The CompAS group meets every year since 2012, with exceptions (2020 and 2021) due to the Covid restrictions:

• Mölle, Sweden, July 6-9, 2012
• Ystad, Sweden, August 10-12, 2013.
• Malmö, Sweden, October 15-17, 2015.
• Malmö/Lund, Sweden, June 1-4, 2016.
• Malmö/Lund, Sweden, August 18-22, 2017.
• Malmö/Lund, Sweden, June 14-18, 2018.
• Brussels, Belgium, November 22-23, 2019.
• Sopot/Gdańsk, Poland, October 1-3, 2022.
• Uppsala, Sweden, June 6-9, 2023.
• Lisbon, Portugal, June 25-28, 2024
• Lund, Sweden, June 12-14, 2025

The CompAS group agreed for the following Copyright recommendations:

If you are using unpublished codes, the CompAS policy is the following order of actions:

1. Invite the authors of the codes to be co-authors,
2. if they decline this, they should at least be referred in “private communication” in your publication.
3. If you are using published codes, cite properly the source publications.

Pages

• List of members
• Summary of research
• List of developed codes
• Authored books
• An, approximately, complete list of scientific publications from all CompAS members (last update: June 23, 2024)

For web admin inquiries, contact Wenxian Li, National Astronomical Observatories/Chinese Academy of Sciences, at wxli[at]nao.cas.cn