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Symmetry components analysis of nuclear spin–spin coupling constants
Author(s) -
Barbier Claudette,
Berthier Gaston
Publication year - 1967
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/qua.560010516
Subject(s) - coupling constant , molecular symmetry , symmetry (geometry) , atomic orbital , coupling (piping) , molecular orbital , chemistry , spin (aerodynamics) , perturbation theory (quantum mechanics) , molecular physics , atomic physics , molecule , physics , quantum mechanics , electron , computational chemistry , thermodynamics , materials science , geometry , mathematics , metallurgy
Molecular symmetry properties are used to define “normal” spin–spin coupling constants corresponding to some irreducible representations of the symmetry point group of the molecule. The relationship between these normal coupling constants and the measured ones is established in closed form for the most common cases. The Ramsey perturbation formula is analysed into symmetry components by means of the Winger–Eckart theorem. Both contributions predicted by the molecular‐orbital method, i. e. direct coupling via σ electrons and indirect coupling via σ–π interaction are studied. Numerical calculations for the coupling constants of ethane, ethylene and acetylene were carried out without the mean excitation energy approximation by using SCF MO wave functions; overlap between atomic orbitals is systematically taken into account by calculating coupling constants. Theoretical and experimental results are compared in terms of symmetry components.