Pj. Stephens et al., AB-INITIO CALCULATION OF VIBRATIONAL ABSORPTION AND CIRCULAR-DICHROISM SPECTRA USING DENSITY-FUNCTIONAL FORCE-FIELDS, Journal of physical chemistry, 98(45), 1994, pp. 11623-11627
The unpolarized absorption and circular dichroism spectra of the funda
mental vibrational transitions of the chiral molecule 4-methyl-2-oxeta
none are calculated ab initio. Harmonic force fields are obtained usin
g density functional theory (DFT), MP2 and SCF methodologies, and a [5
s4p2d/3s2p] (TZ2P) basis set. DFT calculations use the LSDA, BLYP, and
Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using
LSDA, BLYP, and B3LYP force fields are of significantly different qua
lity, the B3LYP force field yielding spectra in clearly superior, and
overall excellent, agreement with experiment. The MP2 force field yiel
ds spectra in slightly worse agreement with experiment than the B3LYP
force field. The SCF force field yields spectra in poor agreement with
experiment. The basis set dependence of B3LYP force fields is also ex
plored: the 6-31G and TZ2P basis sets give very similar results while
the 3-21G basis set yields spectra in substantially worse agreement w
ith experiment.