Modified PCILO method. II. Second-order energy and geometry of transition-metal halides

✍ Scribed by R. Boča; P. Pelikán

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 484 KB
• Volume: 18
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560180603

✦ Synopsis

Abstract

The modified PCILO method, for which the use of the Rayleigh–Schrödinger many‐body perturbation theory with the Møller–Plesset type of Hamiltonian partitioning is characteristic, has been extended to energy calculations of transition metal compounds. On the CNDO/2 level of the Hamiltonian approximation the energy and geometry of the ions Cu__X__~4~^2−^, M__Cl~4~^2−^ and the molecules Cu__X (X = F, Cl, Br; M = Mn, Fe, Co, Ni, Cu) have been calculated. The comparison with MOLCAOSCF calculations (CNDO/2–UHF) shows that the localized bonding model used here can be regarded as a good zeroth‐order approximation describing the bonding situation in complexes of this type. The perturbation theory also provides an improvement of the harmonic force constants of the Cu__X__ molecules with respect to the SCF level of approximation.