The ground-state spectroscopic constants of Be2 revisited

Abstract

Extensive ab initio calibration calculations combined with extrapolations towards the infinite-basis limit lead to a ground-state dissociation energy of

Reexamination of the calculation of two-center, two-electron integrals over Slater-type orbitals. III. Case study of the beryllium dimer

“…The error is simply taken as the (rounded up) value of the corresponding CBS increment. The obtained value is in a moderate agreement with the values given by Patkowski et al [32], −4.1 cm −1 , Martin [33], −4.0 cm −1 , and Gdanitz [34], −5.2 cm −1 . However, as far as we can tell, these values are not extrapolated and the authors report no respective error bars of their result.…”

“…Therefore, we can conclude that CCSDT method in the CBS limit would probably give the core-core and core-valence contribution accurate to within few parts in cm −1 . A similar observation was also made implicitly by Martin [33].…”

“…Our final result, namely 864.9 ± 1.7 cm −1 , is in line with recent findings of other authors. Patkowski et al [32] found 857 ± 12 cm −1 , if we follow their method of error estimation, and Martin [33] gives 872 ± 15 cm −1 . Present result lies well within the error bounds obtained in these works.…”

“…For instance, Martin gives 76.2 cm −1 [33] while Patkowski et al [32] reports as much as 85 ± 5 cm −1 . We believe that these discrepancies are mainly due to defects in the GTOs basis sets used by authors.…”

“…For instance, Martin [33] found 944 ± 25 cm −1 , Gdanitz [34] [37]. Discrepancies between these results are still rather large, though, which indicates that the ground state of the beryllium dimer remains to be a challenge for modern quantum chemistry methods.…”