Quantum chemical calculation of force constants and vibrational spectra

G. Fogarasi, P. Pulay

Research output: Article

29 Citations (Scopus)

Abstract

As a result of the development of direct derivative methods and improved computational facilities, ab initio quantum chemical calculations have become an increasingly important source of information for the determination of molecular force constants. Within the Hartree-Fock (H-F) SCF model and using moderate size basis sets such calculations are now economically feasible for molecules of up to 2o-3o atoms. At this level of theory, harmonic diagonal force constants are overestimated by 1o-3o%, corresponding to 5-15% in the frequencies. However, the largely systematic errors can be accounted for by simple empirical corrections. The resulting SQM (Scaled Quantum Mechanical) force fields are probably the most reliable ones available at present for larger molecules. Calculated infrared intensities are semi-quantitatively correct. Beyond the H-F model, large scale calculations including electron correlation give great improvements in the force constants, but there are still residual errors of a few percent.

Original languageEnglish
Pages (from-to)145-152
Number of pages8
JournalJournal of Molecular Structure
Volume141
Issue numberC
DOIs
Publication statusPublished - 1986

Fingerprint

Vibrational spectra
vibrational spectra
Electrons
Electron correlations
Molecules
Systematic errors
systematic errors
field theory (physics)
self consistent fields
molecules
Infrared radiation
Derivatives
harmonics
Atoms
atoms
electrons

ASJC Scopus subject areas

  • Structural Biology
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Materials Science (miscellaneous)
  • Atomic and Molecular Physics, and Optics

Cite this

Quantum chemical calculation of force constants and vibrational spectra. / Fogarasi, G.; Pulay, P.

In: Journal of Molecular Structure, Vol. 141, No. C, 1986, p. 145-152.

Research output: Article

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