Modification of the NDO model in semiempirical MO theory

✍ Scribed by M. V. Basilevsky; A. G. Shamov

• Book ID: 104579784
• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 376 KB
• Volume: 17
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560170211

✦ Synopsis

Abstract

We suggest the explicit transformation of the parametrized atomic ϕ‐basis semiempirical Hamiltonian to the Löwdin λ basis. A nontrivial problem then arises concerning the transformation of the four‐index electron interaction matrix Γ, for which parametrization is given in the ϕ basis, whereas the NDO approximation is introduced in the λ basis. The main result is that under the CNDO assumption the two‐index Coulomb matrix can be transformed independently of other integrals of Γ. The explicit form of the transformation between the Coulomb matrix γ of parameters given in the ϕ basis and the Coulomb matrix ^λ^γ in the λ basis is found. The ^λ^γ calculated by this method differs only slightly from the result of the exact complicated four‐index transformation. On the other hand the elements of γ and ^λ^γ may differ by several eV when overlap is significant.