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Semi‐empirical MO calculations of nuclear spin coupling constants
Author(s) -
Barbieri Giorgio,
Benassi Rois,
Lazzeretti Paolo,
Taddei Ferdinando
Publication year - 1975
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270071109
Subject(s) - cndo/2 , spin (aerodynamics) , coupling constant , wave function , coupling (piping) , heteroatom , molecule , dirac (video compression format) , electron , computational chemistry , set (abstract data type) , chemistry , quantum mechanics , mathematics , physics , materials science , thermodynamics , computer science , ring (chemistry) , organic chemistry , neutrino , metallurgy , programming language
The results obtained using different semi‐empirical approaches, namely EHMO, IEHMO, CNDO/2 and INDO, in the calculation of spin–spin coupling constants within the framework of the one‐electron MO approximation are systematically compared in the case of several classes of organic molecules. While, at a semi‐empirical level SCF methods normally provide satisfactory wave function, the use of the simple EHMO seems better able to satisfy the problem connected with the calculation of spin–spin coupling constants, expecially when an appropriate set of AO's is chosen, in order to avoid parametrisation of Dirac monocentric integrals. Charge iteration (IEHMO) seems to improve the results slightly only when heteroatoms are present, but the complexity introduced into the calculations and the greatly increased computer time do not justify the slight improvement achieved, particularly as the method is applied to large molecules and organometallic compounds.