Short-time Maximum Entropy Method Analysis of Molecular Dynamics Simulation: Unimolecular Decomposition of Formic Acid

Takahashi Osamu

Nomura Tetsuo

Tabayashi Kiyohiko

Yamasaki Katsuyoshi

Chemical Physics

We performed spectral analysis by using the maximum entropy method instead of the traditional Fourier transform technique to investigate the short-time behavior in molecular systems, such as the energy transfer between vibrational modes and chemical reactions. This procedure was applied to direct ab initio molecular dynamics calculations for the decomposition of formic acid. More reactive trajectories of dehydrolation than those of decarboxylation were obtained for Z-formic acid, which was consistent with the prediction of previous theoretical and experimental studies. Short-time maximum entropy method analyses were performed for typical reactive and nonreactive trajectories. Spectrograms of a reactive trajectory were obtained; these clearly showed the reactant, transient, and product regions, especially for the dehydrolation path.

Classical trajectory calculation

Short-time Fourier transformation

Maximum entropy method

Spectrogram

Formic acid

Chemistry [ 430 ]

eng

Elsevier Science BV

Copyright (c) 2008 Elsevier B.V.

[ISSN] 0301-0104

[DOI] 10.1016/j.chemphys.2008.03.022

[NCID] AA00602111

[DOI] http://dx.doi.org/10.1016/j.chemphys.2008.03.022