https://doi.org/10.1140/epjd/s10053-025-01089-5
Research - Atoms, Molecules, Ions, and Clusters
Study on low-lying states of I₂⁺ and At₂⁺ with equation-of-motion coupled-cluster methods
1
School of Science, Xi’an University of Posts and Telecommunications, 710121, Xi’an, China
2
College of Physics and Optoelectronics Technology, Baoji University of Arts and Sciences, 721016, Baoji, China
Received:
2
September
2025
Accepted:
24
October
2025
Published online:
4
November
2025
The equation-of-motion coupled-cluster (EOM-CC) methods with spin–orbit coupling (SOC) are employed to investigate the low-lying states of I₂⁺ and At₂⁺, where equilibrium bond lengths, harmonic frequencies, vertical electron affinities, adiabatic electron affinities, and adiabatic excitation energies are calculated. Two approximate methods expanded based on EOM-CC method, named EOM-CC(a) and EOM-CC(b), were introduced in order to reduce the computational effort of ionization potentials (IPs) and electron affinities (EAs) from N6 to N5 without significantly sacrificing the accuracy, where N represents the system size. The results indicate that the SOC is more important for the study of heavier open-shell systems. The spectral constants and electronic structural properties of I₂⁺ and At₂⁺ can be calculated well by the EOM-CCSD method with spin–orbit coupling (SOC). It is worth noting that, in the calculation with approximate methods, compared with EOM-CC method, the cost-effective EOM-CC(b) provides satisfactory accuracy in electronic structure calculations for heavier element systems.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
