Halide Ion Micro-Hydration: Structure, Energetics, and Spectroscopy of Small Halide–Water Clusters

<div> <div> <div> <p>Replica exchange molecular dynamics simulations and vibrational spectroscopy calculations are performed using halide-water many-body potential energy functions to provide a bottom-up analysis of the structures, energetics, and hydrogen-bonding arrangements in X−(H2O)n=3−6 clusters, with X = F, Cl, Br, and I. Independently of the cluster size, it is found that all four halides prefer surface-type structures in which they occupy one of the vertices in the underlying three-dimensional hydrogen-bond networks. For fluoride-water clusters, this is in contrast with previous reports suggesting that fluoride prefers interior-type arrangements, where the ion is fully hydrated. These differences can be ascribed to the variability in how various molecular models are capable to reproduce the subtle interplay between halide-water and water-water interactions. Our results thus emphasize the importance of a correct representation of individual many-body contributions to the molecular interactions for a quantitative description of halide ion hydration. </p> </div> </div> </div>

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Data-Driven Many-Body Models with Chemical Accuracy for CH4/H2O Mixtures

10.26434/chemrxiv.13013057 ◽

2020 ◽

Author(s):

Marc Riera ◽

Alan Hirales ◽

Raja Ghosh ◽

Francesco Paesani

Keyword(s):

Liquid Phase ◽

Quantitative Description ◽

Liquid Mixtures ◽

Many Body ◽

Energy Functions ◽

Potential Energy Functions ◽

Dynamics Simulations ◽

Body Potential ◽

Small Clusters ◽

Many Body Interactions

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>

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Chemical Accuracy in Modeling Halide Ion Hydration from Many-Body Representations

10.26434/chemrxiv.6789326.v1 ◽

2018 ◽

Author(s):

Francesco Paesani ◽

Pushp Bajaj ◽

Marc Riera

Keyword(s):

Computer Simulations ◽

Water Clusters ◽

Many Body ◽

Ion Hydration ◽

Systematic Analysis ◽

Ionic Solutions ◽

Potential Energy Functions ◽

The Many ◽

The Individual ◽

Body Potential

<div> <div> <div> <p>Despite the key role that ionic solutions play in several natural and industrial processes, a unified, molecular-level understanding of how ions affect the structure and dynamics of water across different phases remains elusive. In this context, computer simulations can provide new insights that are difficult, if not impossible, to obtain by other means. However, the predictive power of a computer simulation directly depends on the level of “realism” that is used to represent the underlying molecular interactions. Here, we report a systematic analysis of many-body effects in halide-water clusters and demonstrate that the recently developed MB-nrg full-dimensional many-body potential energy functions achieve high accuracy by quantitatively reproducing the individual terms of the many-body expansion of the interaction energy, thus opening the door to realistic computer simulations of ionic solutions. </p> </div> </div> </div>

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Chemical Accuracy in Modeling Halide Ion Hydration from Many-Body Representations

10.26434/chemrxiv.6789326 ◽

2018 ◽

Author(s):

Francesco Paesani ◽

Pushp Bajaj ◽

Marc Riera

Keyword(s):

Computer Simulations ◽

Water Clusters ◽

Many Body ◽

Ion Hydration ◽

Systematic Analysis ◽

Ionic Solutions ◽

Potential Energy Functions ◽

The Many ◽

The Individual ◽

Body Potential

<div> <div> <div> <p>Despite the key role that ionic solutions play in several natural and industrial processes, a unified, molecular-level understanding of how ions affect the structure and dynamics of water across different phases remains elusive. In this context, computer simulations can provide new insights that are difficult, if not impossible, to obtain by other means. However, the predictive power of a computer simulation directly depends on the level of “realism” that is used to represent the underlying molecular interactions. Here, we report a systematic analysis of many-body effects in halide-water clusters and demonstrate that the recently developed MB-nrg full-dimensional many-body potential energy functions achieve high accuracy by quantitatively reproducing the individual terms of the many-body expansion of the interaction energy, thus opening the door to realistic computer simulations of ionic solutions. </p> </div> </div> </div>

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Data-Driven Many-Body Models with Chemical Accuracy for CH4/H2O Mixtures

10.26434/chemrxiv.13013057.v1 ◽

2020 ◽

Author(s):

Marc Riera ◽

Alan Hirales ◽

Raja Ghosh ◽

Francesco Paesani

Keyword(s):

Liquid Phase ◽

Quantitative Description ◽

Liquid Mixtures ◽

Many Body ◽

Energy Functions ◽

Potential Energy Functions ◽

Dynamics Simulations ◽

Body Potential ◽

Small Clusters ◽

Many Body Interactions

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>

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Infrared Signatures of Isomer Selectivity and Symmetry Breaking in the Cs+(H2O)3 Complex Using Many-Body Potential Energy Functions

10.26434/chemrxiv.12275372.v1 ◽

2020 ◽

Author(s):

Marc Riera ◽

Justin J. Talbot ◽

Ryan P. Steele ◽

Francesco Paesani

Keyword(s):

Potential Energy ◽

Potential Energy Surface ◽

Energy Surface ◽

Water Clusters ◽

Quantitative Description ◽

Experimental Spectrum ◽

Many Body ◽

Energy Functions ◽

Potential Energy Functions ◽

Three Body

<div> <div> <div> <p>A quantitative description of the interactions between ions and water is key to characterizing the role played by ions in mediating fundamental processes that take place in aqueous environments. At the molecular level, vibrational spectroscopy provides a unique means to probe the multidimensional potential energy surface of small ion−water clusters. In this study, we combine the MB-nrg potential energy functions recently developed for ion−water interactions with perturbative corrections to vibrational self-consistent field theory and the local-monomer approximation to disentangle many-body effects on the stability and vibrational structure of the Cs+(H2O)3 cluster. Since several low-energy, thermodynamically accessible isomers exist for Cs+(H2O)3, even small changes in the description of the underlying potential energy surface can result in large differences in the relative stability of the various isomers. Our analysis demonstrates that a quantitative account for three-body energies and explicit treatment of cross-monomer vibrational couplings are required to reproduce the experimental spectrum. </p> </div> </div> </div>

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Elevating Density Functional Theory to Chemical Accuracy for Water Simulations through a Density-Corrected Many-Body Formalism

10.33774/chemrxiv-2021-hstgf-v3 ◽

2021 ◽

Author(s):

Saswata Dasgupta ◽

Eleftherios Lambros ◽

John Perdew ◽

Francesco Paesani

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Water Clusters ◽

Potential Energy Function ◽

Data Driven ◽

Coupled Cluster ◽

Many Body ◽

Functional Theory ◽

Dynamics Simulations ◽

Body Potential

Density functional theory (DFT) has been extensively used to model the properties of water. Albeit maintaining a good balance between accuracy and efficiency, no density functional has so far achieved the degree of accuracy necessary to correctly predict the properties of water across the entire phase diagram. Here, we present density-corrected SCAN (DC-SCAN) calculations for water which, minimizing density-driven errors, elevate the accuracy of the SCAN functional to that of “gold standard” coupled-cluster theory. Building upon the accuracy of DC-SCAN within a many-body formalism, we introduce a data-driven many-body potential energy function, MB-SCAN(DC), that quantitatively reproduces coupled cluster reference values for interaction, binding, and individual many-body energies of water clusters. Importantly, molecular dynamics simulations carried out with MB-SCAN(DC) also reproduce the properties of liquid water, which thus demonstrates that MB-SCAN(DC) is effectively the first DFT-based model that correctly describes water from the gas to the liquid phase.

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Infrared Signatures of Isomer Selectivity and Symmetry Breaking in the Cs+(H2O)3 Complex Using Many-Body Potential Energy Functions

10.26434/chemrxiv.12275372 ◽

2020 ◽

Author(s):

Marc Riera ◽

Justin J. Talbot ◽

Ryan P. Steele ◽

Francesco Paesani

Keyword(s):

Potential Energy ◽

Potential Energy Surface ◽

Energy Surface ◽

Water Clusters ◽

Quantitative Description ◽

Experimental Spectrum ◽

Many Body ◽

Energy Functions ◽

Potential Energy Functions ◽

Three Body

<div> <div> <div> <p>A quantitative description of the interactions between ions and water is key to characterizing the role played by ions in mediating fundamental processes that take place in aqueous environments. At the molecular level, vibrational spectroscopy provides a unique means to probe the multidimensional potential energy surface of small ion−water clusters. In this study, we combine the MB-nrg potential energy functions recently developed for ion−water interactions with perturbative corrections to vibrational self-consistent field theory and the local-monomer approximation to disentangle many-body effects on the stability and vibrational structure of the Cs+(H2O)3 cluster. Since several low-energy, thermodynamically accessible isomers exist for Cs+(H2O)3, even small changes in the description of the underlying potential energy surface can result in large differences in the relative stability of the various isomers. Our analysis demonstrates that a quantitative account for three-body energies and explicit treatment of cross-monomer vibrational couplings are required to reproduce the experimental spectrum. </p> </div> </div> </div>

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Elevating density functional theory to chemical accuracy for water simulations through a density-corrected many-body formalism

Nature Communications ◽

10.1038/s41467-021-26618-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Saswata Dasgupta ◽

Eleftherios Lambros ◽

John P. Perdew ◽

Francesco Paesani

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Water Clusters ◽

Potential Energy Function ◽

Data Driven ◽

Coupled Cluster ◽

Many Body ◽

Functional Theory ◽

Dynamics Simulations ◽

Body Potential

AbstractDensity functional theory (DFT) has been extensively used to model the properties of water. Albeit maintaining a good balance between accuracy and efficiency, no density functional has so far achieved the degree of accuracy necessary to correctly predict the properties of water across the entire phase diagram. Here, we present density-corrected SCAN (DC-SCAN) calculations for water which, minimizing density-driven errors, elevate the accuracy of the SCAN functional to that of “gold standard” coupled-cluster theory. Building upon the accuracy of DC-SCAN within a many-body formalism, we introduce a data-driven many-body potential energy function, MB-SCAN(DC), that quantitatively reproduces coupled cluster reference values for interaction, binding, and individual many-body energies of water clusters. Importantly, molecular dynamics simulations carried out with MB-SCAN(DC) also reproduce the properties of liquid water, which thus demonstrates that MB-SCAN(DC) is effectively the first DFT-based model that correctly describes water from the gas to the liquid phase.

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