From atomic and molecular orbitals to chemical orbitals

Authors


  • Partially presented at the 33rd QUITEL, September 19–22, 2007 and at the ICCMSE, September 25–30, 2007, honoring Prof. Yngve Öhrn.

Abstract

In this work, we analyze the molecular orbitals (MO) one-electron functions of the Hartree-Fock (HF) model and the atomic orbitals (AO) of the Heitler-London (HL) and valence bond (VB) models. The complementarity of MO with AO orbitals has been evidenced with the recent Hartree-Fock-Heitler-London model. We propose a new and general one-electron function, the chemical orbital (CO) and the corresponding determinantal wave function, the chemical orbital wave function, ΨCO. We show that the ΨCO can be decomposed into a specific HF-HL function with ionic components, designated “adjoined HF-HL function” and that the HF-HL, HF, and VB wave functions can be derived from the ΨCO wave function. A single “adjoined HF-HL function” can realistically represent molecular systems from the united atom, to equilibrium distances, to dissociation; short linear expansions of “adjoined HF-HL functions” yield accurate nonrelativistic energies. Preliminary test computations with “adjoined HF-HL functions” are presented for the ground state of the H2 and LiH molecules © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008

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