Reassessing spin-coupled (full generalized valence bond) descriptions of ozone using three-center bond indices

Cooper, David L ORCID: 0000-0003-0639-0794, Penotti, Fabio E and Ponec, Robert (2017) Reassessing spin-coupled (full generalized valence bond) descriptions of ozone using three-center bond indices. COMPUTATIONAL AND THEORETICAL CHEMISTRY, 1116. pp. 40-49.

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Official URL: http://dx.doi.org/10.1016/j.comptc.2016.12.010

Abstract

Domain-averaged Fermi hole analysis is carried out for the ground state of O3 at its equilibrium geometry using a complete-active-space self-consistent field CASSCF(18,14) wavefunction, based on a slightly expanded full-valence active space. This initial analysis is augmented with an examination of the corresponding localized natural orbitals (LNOs) and of the numerical values obtained with a new improved definition of three-center bond indices for correlated singlet systems. Much the same pattern of LNOs is observed when using instead a subsequent internally-contracted multiconfiguration-reference configuration interaction construction, which also provides very similar values for the three-center bond indices. This gives us confidence to use such bond indices, alongside relative energies and the electric dipole moment, to assess the relative merits of various combinations of spin-coupled (full generalized valence bond) components with ten active electrons: four π, four σ bonding and the two nonbonding σ electrons associated with the central O atom. These multi-component valence bond descriptions were generated either with or without subsequent orbital reoptimization. The description of the π system which emerges from all of our analysis conforms to a standard model of three-center four-electron π bonding that incorporates a nontrivial degree of (partial) diradical character. Whereas certain combinations of ten-electron spin-coupled components can faithfully reproduce such a picture, none of the individual rival components appears to have sufficient flexibility on its own.

Item Type:	Article
Uncontrolled Keywords:	it system in O-3, Full-GVB and spin-coupled, QTAIM-generalized three-center bond index, Domain-averaged Fermi holes, Localized natural orbitals
Depositing User:	Symplectic Admin
Date Deposited:	07 Dec 2016 09:59
Last Modified:	19 Jan 2023 07:24
DOI:	10.1016/j.comptc.2016.12.010
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3004791