The experimental design for computing the harmonic and anharmonic force constant matrices of polyatomic molecules

Sana, M.
(1982) Theoretica Chimica Acta — Vol. 60, n° 6, p. 543-549 (1982)

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Authors
  • Sana, M.
    Author
Abstract
The author proposes a numerical approach to estimate the harmonic and anharmonic force constant matrices, assuming one is able to compute analytically the first order derivative vector of the potential energy surface with respect to the internal coordinates. He uses a polynomial least square fit to interpolate this gradient in the stationary point region. The structure of the regression matrix shows that the harmonic force constant matrix may be obtained even for large molecules; the evaluation of the anharmonic contributions request slightly more labour but is possible for 5 to 7 atoms. The author's work is applicable even at the CI level and the number of computations remains small. He uses the experimental planification to select the geometries to be computed in order to improve the estimation of the regression coefficients, i.e. to lower their variance.
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Sana, M. (1982). The experimental design for computing the harmonic and anharmonic force constant matrices of polyatomic molecules. Theoretica Chimica Acta, 60(6), 543-549. https://doi.org/10.1007/BF00549610 (Original work published 1982)