Quantum Proton Transfer in Hydrated Sulfuric Acid Clusters: A Perspective from Semiempirical Path Integral Simulations

Sugawara, Shuichi; Yoshikawa, Takehiro; Takayanagi, Toshiyuki; Shiga, Motoyuki; Tachikawa, Masanori

doi:10.1021/jp202380h

Cited by 22 publications

(19 citation statements)

References 57 publications

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“…112 Sugawara et al used path integral molecular dynamics (PIMD) simulations with modified PM6 parameters and predicted an onset of acid dissociation starting at n = 10− 12. 118 The first acid dissociation of sulfuric acid occurs after hydration with as little as four water molecules. 84 In a bulk solution or small aerosols, it is expected that H 2 SO 4 , HSO 4 − , and the SO 4 2− will all be present in equilibrium.…”

Section: Discussionmentioning

confidence: 99%

Hydration of the Bisulfate Ion: Atmospheric Implications

et al. 2012

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Using molecular dynamics configurational sampling combined with ab initio energy calculations, we determined the low energy isomers of the bisulfate hydrates. We calculated the CCSD(T) complete basis set (CBS) binding electronic and Gibbs free energies for 53 low energy isomers of HSO(4)(-)(H(2)O)(n=1-6) and derived the thermodynamics of adding waters sequentially to the bisulfate ion and its hydrates. Comparing the HSO(4)(-)/H(2)O system to the neutral H(2)SO(4)/H(2)O cluster, water binds more strongly to the anion than it does to the neutral molecules. The difference in the binding thermodynamics of HSO(4)(-)/H(2)O and H(2)SO(4)/H(2)O systems decreases with increasing number of waters. The thermodynamics for the formation of HSO(4)(-)(H(2)O)(n=1-5) is favorable at 298.15 K, and that of HSO(4)(-)(H(2)O)(n=1-6) is favorable for T < 273.15 K. The HSO(4)(-) ion is almost always hydrated at temperatures and relative humidity values encountered in the troposphere. Because the bisulfate ion binds more strongly to sulfuric acid than it does to water, it is expected to play a role in ion-induced nucleation by forming a strong complex with sulfuric acid and water, thus facilitating the formation of a critical nucleus.

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Section: Discussionmentioning

confidence: 99%

Hydration of the Bisulfate Ion: Atmospheric Implications

et al. 2012

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“…At the most fundamental level, molecular interaction models based on ab initio quantum mechanics are available. Indeed, very detailed studies have been conducted, even taking account of the quantum nature of the lighter nuclei present [13,14] in addition to that of the electrons. In a structural study of the system that we consider in this paper, for example, Kakizaki et al [13] concluded that nuclear zero point motion in clusters of sulphuric acid and water at 250 K gives rise to noticeably increased fluctuations and liquid-like behaviour.…”

Section: Introductionmentioning

confidence: 99%

A classical reactive potential for molecular clusters of sulphuric acid and water

2015

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We present a two-state empirical valence bond (EVB) potential describing interactions between sulphuric acid and water molecules and designed to model proton transfer between them within a classical dynamical framework. The potential has been developed in order to study the properties of molecular clusters of these species, which are thought to be relevant to atmospheric aerosol nucleation. The particle swarm optimisation method has been used to fit the parameters of the EVB model to density functional theory (DFT) calculations. Features of the parametrised model and DFT data are compared and found to be in satisfactory agreement. In particular, it is found that a single sulphuric acid molecule will donate a proton when clustered with four water molecules at 300 K and that this threshold is temperature dependent.

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“…The PIMD method has been shown to have a significant effect on the properties in some hydrogen bonded systems 23,24 . PIMD has been employed previously together with a parametrised version of the PM6 model 25 (a semi-empirical model of electronic structure) to study sulphuric acid and water clusters 26,27 . Kakizaki et al 26 concluded that the PIMD technique (using the normal mode transformation 22 ) increased thermal fluctuations and produced more liquid-like behaviour in systems at a temperature of 250 K 26 .…”

Section: Introductionmentioning

confidence: 99%

Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

Stinson

Kathmann

Ford

2014

The Journal of Chemical Physics

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The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei (CCN), and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nuclei have a classical nature, which is questionable for some systems. The importance of zero-point motion (also known as quantum nuclear dynamics) in modelling small clusters of sulphuric acid and water is tested here using the path integral molecular dynamics (PIMD) method at the density functional theory (DFT) level of theory. The general effect of zeropoint motion is to distort the mean structure slightly, and to promote the extent of proton transfer with respect to classical behaviour. In a particular configuration of one sulphuric acid molecule with three waters, the range of positions explored by a proton between a sulphuric acid and a water molecule at 300 K (a broad range in contrast to the confinement suggested by geometry optimisation at 0 K) is clearly affected by the inclusion of zero point motion, and similar effects are observed for other configurations.

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Quantum Proton Transfer in Hydrated Sulfuric Acid Clusters: A Perspective from Semiempirical Path Integral Simulations

Cited by 22 publications

References 57 publications

Hydration of the Bisulfate Ion: Atmospheric Implications

Hydration of the Bisulfate Ion: Atmospheric Implications

A classical reactive potential for molecular clusters of sulphuric acid and water

Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

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