Premium
Barriers to rotation adjacent to double bonds. 4. Effect of basis set on structures, and of electron correlation on relative energies
Author(s) -
Wiberg Kenneth B.,
Murcko Mark A.
Publication year - 1988
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540090507
Subject(s) - electronic correlation , chemistry , isobutyraldehyde , basis set , conformational isomerism , gaussian orbital , rotation (mathematics) , computational chemistry , ab initio , molecule , molecular physics , density functional theory , geometry , mathematics , organic chemistry , catalysis
The optimized geometries for the rotamers of propanal, 2‐butanone, isobutyraldehyde, methyl isopropyl ketone, and isobutyric acid obtained using the 3–21G and 6–31G* basis sets are compared, and systematic changes are noted. The relative 6–31G* energies using the 3–21G and 6–31G* geometries are generally the same within 0.1 kcal/mol. The effect of electron correlation on the relative energies is generally small. These and related data show that 6–31G* relative energies obtained using 3–21G geometries are generally satisfactory when studying rotation about CC bonds. However, this is not the case for CO bonds. The calculated relative energies of isomeric compounds are reproduced only with the full MP4 correction for electron correlation.