A pure H2O isolated line-shape model based on classical molecular dynamics simulations of velocity changes and semi-classical calculations of speed-dependent collisional parameters

作者：Ngo N H; Tran H^*; Gamache R R

来源：Journal of Chemical Physics, 2012, 136(15): 154310.

DOI：10.1063/1.4704675

It is well known that the Voigt profile does not well describe the (measured) shapes of isolated lines. This is due to the neglect of the intermolecular collision-induced velocity changes and of the speed dependence of the collisional parameters. In this paper, we present a new line profile model for pure H2O which takes both of these effects into account. The speed dependence of the collisional parameters has been calculated by a semi-classical method. The velocity changes have been modeled by using the Keilson-Storer collision kernel with two characteristic parameters. The latter have been deduced from classical molecular dynamics simulations which also indicate that, for pure H2O, the correlation between velocity-changing and state-changing collisions is not negligible, a result confirmed by the analysis of measured spectra. A partially correlated speed-dependent Keilson-Storer model has thus been adopted to describe the line-shape. Comparisons between simulated spectra and measurements for four self-broadened lines in the near-infrared at various pressures show excellent agreements.

• 出版日期2012-4-21