The accuracy of the pseudopotential approximation: non-frozen-core effects for spectroscopic constants of alkali fluorides XF (X = K, Rb, Cs)
✍ Scribed by Thierry Leininger; Andreas Nicklass; Wolfgang Küchle; Hermann Stoll; Michael Dolg; Andreas Bergner
- Book ID
- 103036212
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 470 KB
- Volume
- 255
- Category
- Article
- ISSN
- 0009-2614
No coin nor oath required. For personal study only.
✦ Synopsis
The performance of large-core pseudopotentials (ECP), simulating X + cores (X = K, Rb, Cs), and corresponding core-polarization potentials (CPP) is critically analyzed in calculations for bond lengths re, dissociation energies D e, and vibrational frequencies to e of alkali fluorides XF. It is shown that significant errors arise due to both the ECP modelling of the frozen-core-valence interaction and the CPP treatment of non-frozen-core effects. Correcting for these errors, by introducing small-core ECP and /-dependent CPP, we obtain accuracies of 1 pm for re, 0.1 eV for D e and 5 cm -1 for oJ e, in coupled cluster calculations using extended basis sets.