Coulomb Hybrid Two-Electron Integrals for Transition Metal Atoms: Comparison of Theoretical Integrals with those Evaluated from Spectroscopic Data
When investigating the electronic structure of transition metal systems by quantum-chemical approaches based on the NDDO approximation, the so-called one-centre hybrid Coulomb integrals are required. These integrals are expressed in terms of the Slater-Condon parameters (SCP) R(k)(abcd) with different radial functions a, b, c, d. One can obtain these SCP's by two ways. First, the direct integration with Slater-type orbitals is used. And secondly, one can fit R(k) from atomic spectra by taking into account the configurational interaction. As an example the R1(sdpp), R2(sdpp) and R2(sdpp) SCP's for Ti2+ have been evaluated. Comparison of the fitted values with theoretical integrals indicates that the latter are substantially smaller.