Ab initio Potential Energy Curve for the Ground State of Beryllium Dimer

• Published in: Journal of chemical theory and computation Vol. 15; no. 4; pp. 2470 - 2480
• Main Authors: Lesiuk, Michał, Przybytek, Michał, Balcerzak, Justyna G, Musiał, Monika, Moszynski, Robert
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.04.2019
• Subjects: Beryllium; Dimers; Electronic structure; Energy of dissociation; Free energy; Ground state; Heat of formation; Potential energy; Quantum electrodynamics; Relativity
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/acs.jctc.8b00845

This work concerns ab initio calculations of the complete potential energy curve and spectroscopic constants for the ground state X 1Σ g + of the beryllium dimer, Be2. High accuracy and reliability of the results is one of the primary goals of the paper. To this end, we apply large basis sets of Slater-type orbitals combined with high-level electronic structure methods including triple and quadruple excitations. The effects of the relativity are also fully accounted for in the theoretical description. For the first time the leading-order quantum electrodynamics effects are fully incorporated for a many-electron molecule. Influence of the finite nuclear mass corrections (post-Born–Oppenheimer effects) turns out to be completely negligible for this system. The predicted well-depth (D e = 934.6 ± 2.5 cm–1) and the dissociation energy (D 0 = 807.7 cm–1) are in a very good agreement with the most recent experimental data. We confirm the existence of the weakly bound twelfth vibrational level [Patkowski et al. Science 2009, 326, 1382] that it lies just below the onset of the continuum.