26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Improved structure calculations in open-shell atoms and applications to EUV lithography

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Atomic and Molecular Physics (ATMOP)

Speaker

Julian Berengut (University of New South Wales)

Description

We present recent theoretical and computational updates to the CI+MBPT method (configuration interaction with many-body perturbation theory) as implemented in AMBiT [1]. The efficiency gains have been orders-of-magnitude and have enabled the complete saturation of CI in large open-shell atoms. Taken with treatment of core-valence correlations using MBPT, we produce the emission spectrum of Sn12+ ions in the range of multilayer mirrors [2]. Unlike previous calculations, we reproduce the observed peak in the emission spectrum without the need for semi-empirical corrections that redshift the spectrum. We find a surprisingly large influence of highly-excited states on the in-band EUV light production, which is critical to the efficiency of EUV lithography.

[1] E. V. Kahl and J. C. Berengut, Comput. Phys. Commun., 238, 232 (2019).
[2] M. L. Reitsma, J. Sheil, O. O. Versolato, E. V. Kahl, and J. C. Berengut, arXiv:2606.04868 (2026).