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Two‐dimensional treatment of the aldehydic carbonyl torsion and hydrogen wagging in gas‐phase propanal
Author(s) -
VivierBunge A.,
Uc V. H.,
Smeyers Y. G.
Publication year - 1999
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(1999)72:4<411::aid-qua25>3.0.co;2-9
Subject(s) - chemistry , conformational isomerism , torsion (gastropod) , excited state , hydrogen , dipole , potential energy surface , aldehyde , gas phase , photochemistry , potential energy , computational chemistry , atomic physics , ab initio , molecule , organic chemistry , physics , catalysis , medicine , surgery
The potential energy surface for the simultaneous aldehydic carbonyl torsion and hydrogen wagging in propanal has been determined at RHF/MP2 level using the 6‐311G(3df, p) basis set. Sixty‐three energy values were fitted to an analytic form of C S symmetry. With this potential, as well as with the kinetic parameters and the electric dipole moment variations, the far infrared (FIR) frequencies and intensities for the aldehydic carbonyl torsion and hydrogen wagging were determined theoretically. It is found that the two‐dimensional calculation for the cis conformer satisfactorily reproduces not only the asymmetric aldehyde torsion spectrum, but yields also a torsionally excited progression for the aldehydic hydrogen wagging modes. Finally, the introduction of the aldehydic hydrogen wagging mode in the calculations is seen to enhance significantly the intensities the carbonyl torsion bands. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 411–420, 1999