Modeling the electronic structures of the ground and excited states of the ytterbium atom and the ytterbium dimer: A modern quantum chemistry perspective |
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Authors: | Paweł Tecmer Katharina Boguslawski Mateusz Borkowski Piotr S Żuchowski Dariusz Kędziera |
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Institution: | 1. Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Torun, Poland;2. Department of Chemistry, Nicolaus Copernicus University in Torun, Torun, Poland |
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Abstract: | We present a comprehensive theoretical study of the electronic structures of the Yb atom and the Yb2 molecule, respectively, focusing on their ground and lowest-lying electronically excited states. Our study includes various state-of-the-art quantum chemistry methods such as CCSD, CCSD(T), CASPT2 (including spin-orbit coupling), and EOM-CCSD as well as some recently developed pCCD-based approaches and their extensions to target excited states. Specifically, we scan the lowest-lying potential energy surfaces of the Yb2 dimer and provide a reliable benchmark set of spectroscopic parameters including optimal bond lengths, vibrational frequencies, potential energy depths, and adiabatic excitation energies. Our in-depth analysis unravels the complex nature of the electronic spectrum of Yb2, which is difficult to model accurately by any conventional quantum chemistry method. Finally, we scrutinize the bi-excited character of the first excited state and its evolution along the potential energy surface. |
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Keywords: | relativistic effects electron corellation effects spin-orbit coupling equation of motion coupled cluster CASPT2 |
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