A LOCAL APPROXIMATION FOR RELATIVISTIC SCALAR OPERATORS APPLIED TO THE URANYL-ION AND TO AU-2

The one-center approximation has been shown to be accurate in spin-orb it calculations, and in the present study this approach is extended to the scalar relativistic case. Results obtained on the uranyl ion and on Au-2 are in agreement with fully relativistic one-component calcula tions, provided that the deep core, taken from the separate atoms, is kept frozen. It is also shown that the one-center approximation with f rozen cores gives reliable results in geometry optimizations using gra dient techniques. Published by Elsevier Science B.V.