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• Chinese Journal of Chemical Physics
• Vol. 33, Issue 5, 05000613 (2020)
Zhang Zhi-jun, Chen Zi-fei, and Liu Jian*

Abstract

Formaldehyde and hydrogen peroxide are two important realistic molecules in atmospheric chemistry. We implement path integral Liouville dynamics (PILD) to calculate the dipole-derivative autocorrelation function for obtaining the infrared spectrum. In comparison to exact vibrational frequencies, PILD faithfully captures most nuclear quantum effects in vibrational dynamics as temperature changes and as the isotopic substitution occurs.

Ⅰ INTRODUCTION

It is challenging to include nuclear quantum effects (NQEs) for chemical dynamics of molecular systems. Most trajectory-based quantum dynamics methods fail to satisfy the two important properties simultaneously [1-8]: (ⅰ) conserve the quantum canonical distribution for a thermal equilibrium system, and (ⅱ) recover exact quantum correlation functions in the harmonic limit for both linear and nonlinear operators (i.e. linear or nonlinear functions of position or momentum operators). Recently developed path integral Liouville dynamics (PILD) is able to have these two properties, as well as yields exact correlation functions in the classical ($\hbar \rightarrow$0) and high-temperature ($\beta \rightarrow$0) limits. PILD has been shown to be a useful approach to compute vibrational spectra of realistic molecular systems, which leads to a reasonably accurate peak position with a relatively small full width at half maximum (FWHM) for an excited mode [9].

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Zhi-jun Zhang, Zi-fei Chen, Jian Liu. Path Integral Liouville Dynamics Simulations of Vibrational Spectra of Formaldehyde and Hydrogen Peroxide[J]. Chinese Journal of Chemical Physics, 2020, 33(5): 613