Journal of Chemical Physics, Vol.104, No.11, 4061-4067, 1996
On the Accuracy of Valence Correlation Energies in Pseudopotential Calculations
Total valence correlation energies of X(5+), X(+), X, X(-), and X(2) (X=F,Cl,Br,I) have been calculated with the coupled-cluster method for the all-electron and the pseudopotential case using large uncontracted basis sets containing up to g-type functions. The overestimation of valence correlation energies due to the modified nodal structure of the pseudo-orbitals is discussed. The errors are found to be less than 10% in all cases of chemical interest and reduce to 2 mH or less in correlation contributions to ionization potentials, electron affinities or binding energies.
Keywords:RELATIVISTIC EFFECTIVE POTENTIALS;SPIN-ORBIT OPERATORS;CONFIGURATION-INTERACTION CALCULATIONS;EFFECTIVE CORE POTENTIALS;MAIN GROUP ELEMENTS;MOLECULAR CALCULATIONS;ABINITIO