Hg. Kjaergaard et al., THE ROLE OF ELECTRON CORRELATION ON CALCULATED XH-STRETCHING VIBRATIONAL BAND INTENSITIES, Molecular physics, 90(2), 1997, pp. 201-213
XH-stretching vibrational band intensities have been calculated for se
ven small molecules with OH, NH and CH bonds, respectively, using the
simple harmonically coupled anharmonic oscillator local mode model and
ab initio dipole moment functions, both expressed in XH-stretching bo
nd coordinates. The dipole moment functions were calculated with a tri
ple valence basis set including both diffuse and multiple polarization
functions, and at different levels of ab initio theory. The self-cons
istent field Hartree-Fock calculation is compared with different ways
of including electron correlation. These calculations show that in gen
eral electron correlation in the ab initio calculation of the dipole m
oment function is often important in predictions of fundamental XH-str
etching band intensities, whereas the XH-stretching overtone intensiti
es are insensitive to electron correlation. This insight is important
for studies of larger molecules where the highest levels of theory are
not computationally feasible.