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Valence bond studies of the D 2 h isomer of O 4 : An interim report
Author(s) -
Harcourt Richard D.
Publication year - 1997
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1997)63:2<547::aid-qua24>3.0.co;2-3
Subject(s) - dimer , chemistry , ionic bonding , valence (chemistry) , covalent bond , valence bond theory , ab initio , monomer , computational chemistry , basis set , crystallography , resonance (particle physics) , molecule , atomic physics , density functional theory , molecular orbital , physics , organic chemistry , ion , polymer
Single‐zeta and π‐electron double‐zeta basis sets are used to examine some theories of the origin of the stability of the D 2 h isomer of O 4 , using ab initio valence‐bond procedures. With these basis sets, resonance between covalent‐type (i.e., O 2 ·· O 2 ) valence‐bond structures does not lead to a stabilization of the dimer relative to the separated monomers. When basis sets of the same size are used to construct wave functions for covalent and ionic structures, covalent‐ionic resonance (i.e., O 2 ·· O 2 ↔ O 2 + ·· O 2 − ↔ O 2 − ·· O 2 + ) is also unable to stabilize the dimer. Without consideration of the basis‐set superposition error, stability is obtained when the size of the AO basis is increased for the dimer relative to the monomer, either via the basis for the ionic structures or by the inclusion of midbond functions. Brief consideration is given to an increased‐valence structure for the dimer. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 547–555, 1997