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2D IR spectra of cyanide in water investigated by molecular dynamics simulations

Journal of Chemical Physics

By:
, , , ,
DOI: 10.1063/1.4815969

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Abstract

Using classical molecular dynamics simulations, the 2D infrared (IR) spectroscopy of CN solvated in D2O is investigated. Depending on the force field parametrizations, most of which are based on multipolar interactions for the CN molecule, the frequency-frequency correlation function and observables computed from it differ. Most notably, models based on multipoles for CN and TIP3P for water yield quantitatively correct results when compared with experiments. Furthermore, the recent finding that T 1 times are sensitive to the van der Waals ranges on the CN is confirmed in the present study. For the linear IR spectrum, the best model reproduces the full widths at half maximum almost quantitatively (13.0 cm−1 vs. 14.9 cm−1) if the rotational contribution to the linewidth is included. Without the rotational contribution, the lines are too narrow by about a factor of two, which agrees with Raman and IR experiments. The computed and experimental tilt angles (or nodal slopes) α as a function of the 2D IR waiting time compare favorably with the measured ones and the frequency fluctuation correlation function is invariably found to contain three time scales: a sub-ps, 1 ps, and one on the 10-ps time scale. These time scales are discussed in terms of the structural dynamics of the surrounding solvent and it is found that the longest time scale (≈10 ps) most likely corresponds to solvent exchange between the first and second solvation shell, in agreement with interpretations from nuclear magnetic resonance measurements.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
2D IR spectra of cyanide in water investigated by molecular dynamics simulations
Series title:
Journal of Chemical Physics
DOI:
10.1063/1.4815969
Volume
139
Issue:
5
Year Published:
2013
Language:
English
Publisher:
American Institute of Physics
Publisher location:
New York, NY
Description:
13 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1
Last page:
12
Number of Pages:
13