Determination of one-centre core integrals from the average energies of atomic configurations

✍ Scribed by Göran Karlsson; Michael C. Zerner

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 628 KB
• Volume: 7
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560070106

✦ Synopsis

Abstract

One‐center core integrals for valence orbitals are determined from the experimental average energies of neutral atomic configurations from Li through Zn. These values are compared with those estimated from CNDO/1, “INDO/1”, CNDO/2, “INDO/2” and with theoretical values calculated from a pseudo‐potential method. The agreement is good between values obtained from neutral atoms and from the psuedo‐potential calculation except for the 3__d__ orbitals of the transition elements where the theoretically calculated integrals over single ξ functions are not realistic. These two methods reproduce both term and average configuration energies for the first two rows of atoms; the semiempirical method reliably reproduces them for the third row. The CNDO/1 and INDO/1 methods underestimate atomic energies, while the CNDO/2 and INDO/2 procedures fail rather poorly.

The propriety of using core integrals estimated semiempirically in molecular orbital calculations is discussed.