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

Abstract

This work concerns ab initio calculations of the complete potential energy curve and spectroscopic constants for the ground state X 1 Σ + g of the beryllium dimer, Be 2 .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 highlevel 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 = 934.5 ± 2.5 cm −1 ) and the dissociation energy (D 0 = 808.0 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 326, 1382(2009] and predict that it lies just about 0.5 cm −1 below the onset of the continuum.

On rotational-vibrational spectrum of diatomic beryllium molecule

“…Similar results have been obtained in Ref. [9]. The main attention in the optimization of the MLR and CPE functions was focused on their correct long-range behavior displayed in Fig.…”

Revisiting the Intriguing Electronic Features of the BeOBeC Carbyne and Some Isomers: A Quantum‐Chemical Assessment

“…As mentioned by Merritt et al., more than one hundred, often contradicting theoretical investigations on Be 2 had already been published by 2009 . Recently, in an extraordinarily demanding tour‐de‐force, the complete PES and the spectroscopic constants were reported for the ground state of X 1 Σ g + of Be 2 , and this study emphasizes the need for both a proper theoretical method and adequate basis sets to cope with the often multireference character of these species.…”

“…Note that the energy of 1 Be 2 +CO was derived by calculating the relative energy of 1 Be 2 and 3 Be 2 using CASPT2(4e,8o)/aug‐cc‐pVQZ due to the multireference character of the beryllium dimer (ref. ). Bond lengths of Be 2 in brackets are obtained using CASPT2/aug‐cc‐pVQZ.…”

Revisiting the Intriguing Electronic Features of the BeOBeC Carbyne and Some Isomers: A Quantum‐Chemical Assessment

“…In fact, the Be 2 case was considered "pathological". [19] As mentioned by Merritt et al, more than one hundred, often contradicting theoretical investigations on Be 2 had already been published by 2009. [19a] Recently, in an extraordinarily demanding tour-de-force, the complete PES and the spectroscopic constants were reported for the ground state of X 1 S g + of Be 2 , [19b] and this study emphasizes the need for both a proper theoretical method and adequate basis sets to cope with the often multireference character of these species.…”