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Issue 28, 2008
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Analytic three-dimensional ‘MLR’ potential energy surface for CO2–He, and its predicted microwave and infrared spectra

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Abstract

A three-dimensional, analytic potential energy surface for CO2–He that explicitly incorporates its dependence on the Q3 asymmetric-stretch normal-mode coordinate of the CO2 monomer has been obtained by least-squares fitting new ab initio interaction energies to a new three-dimensional Morse/Long-Range (3D-MLR) potential function form. This fit to 2832 points has a root-mean-square (RMS) deviation of 0.032 cm−1 and requires only 55 parameters. The resulting pure ab initio potential provides a good representation of the experimental microwave and infrared data: for 51 pseudo microwave and 49 infrared transitions the RMS discrepancies are 0.0110 and 0.0445 cm−1, respectively. Scaling this surface using only two morphing parameters yields an order of magnitude better agreement with experiments, with RMS discrepancies of only 0.0025 and 0.0038 cm−1, respectively. The calculated infrared band origin shift associated with the ν3 fundamental of CO2 is 0.109 cm−1, in good agreement with the (extrapolated) experimental value of 0.095 cm−1.

Graphical abstract: Analytic three-dimensional ‘MLR’ potential energy surface for CO2–He, and its predicted microwave and infrared spectra

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Publication details

The article was received on 15 Jan 2008, accepted on 11 Apr 2008 and first published on 04 Jun 2008


Article type: Paper
DOI: 10.1039/B800718G
Citation: Phys. Chem. Chem. Phys., 2008,10, 4128-4137
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    Analytic three-dimensional ‘MLR’ potential energy surface for CO2–He, and its predicted microwave and infrared spectra

    H. Li and R. J. Le Roy, Phys. Chem. Chem. Phys., 2008, 10, 4128
    DOI: 10.1039/B800718G

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