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Pople, J.A., Schlegel, H.B., Krishnan, R., Defrees, D.J., Binkley, J.S., Frisch, M.J., Whiteside, R.A., Hout, R.F. and Hehre, W.J. (1981) Molecular-Orbital Studies of Vibrational Frequencies. International Journal of Quantum Chemistry, 20, 269-278. http://dx.doi.org/10.1002/qua.560200829

has been cited by the following article:

• TITLE: Reduced Partition Function Ratio in the Frequency Complex Plane: A Mathematical Approach

  AUTHORS: Jie Yuan

  KEYWORDS: Isotope Fractionation, Cluster, Reduced Partition Function Ratio, Frequency Complex Plane

  JOURNAL NAME: Open Journal of Geology, Vol.4 No.12, December 31, 2014

  ABSTRACT: This paper gives a mathematical approach to calculate the fractionation factor of isotopes in a general cluster (also known assuper-molecule), which composes of necessary chemical effect within three bonds outside the interested atom(s). The cluster might have imaginary frequencies after being optimized in quantum softwares. The approach includes the contribution of the difference, which is resulted from the substitution of heavy and light isotopes in the cluster, of vibrations of imaginary frequencies to give precise prediction of isotope fractionation factor. We call the new mathematical approximation “reduced partition function ratio in the frequency complex plane (RPFRC)”. If there is no imaginary frequency for a cluster, RPFRCis simplified to be Urey (1947) or Bigeleisen and Mayer (1947) formula. Final results of this new algorithm are in good agreement with those in earlier studies.