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Reassessing Spin-Coupled (Full Generalized Valence Bond) Descriptions of Ozone Using Three-Center Bond Indices.

SYSNO ASEP	0480523
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Reassessing Spin-Coupled (Full Generalized Valence Bond) Descriptions of Ozone Using Three-Center Bond Indices.
Author(s)	Cooper, D.L. (GB) Penotti, F.E. (IT) Ponec, Robert (UCHP-M)_{RID, ORCID, SAI}
Source Title	Computational and Theoretical Chemistry - ISSN 2210-271X Roč. 1116, Sl (2017), s. 40-49
Number of pages	10 s.
Language	eng - English
Country	NL - Netherlands
Keywords	full GVB and spin-coupled ; PI-system in O3 ; domain-averaged fermi holes
Subject RIV	CF - Physical ; Theoretical Chemistry
OECD category	Physical chemistry
Institutional support	UCHP-M - RVO:67985858
UT WOS	000409152500004
EID SCOPUS	85008173487
DOI	10.1016/j.comptc.2016.12.010
Annotation	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.
Workplace	Institute of Chemical Process Fundamentals
Contact	Eva Jirsová, jirsova@icpf.cas.cz, Tel.: 220 390 227
Year of Publishing	2018

Number of the records: 1