Benchmark Electronic Structure Calculations for H3O+(H2O)n, n = 0–5, Clusters and Tests of an Existing 1,2,3-Body Potential Energy Surface with a New 4-Body Correction

Heindel, Joseph P.; Yu, Qi; Bowman, Joel M.; Xantheas, Sotiris S.

doi:10.1021/acs.jctc.8b00598

Cited by 41 publications

(93 citation statements)

References 64 publications

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“…11 for more examples. Being usually based on many-body expansions, such approaches were also recently applied to protonated water clusters, explicitly including up to four body terms 12 , and shown to reproduce coupled cluster reference calculations with rather high accuracy for stationary point structures. Other notable potentials for protonated water (clusters) rely on empirical models 13 , perturbation theory 14 , or are based on empirical valence bond models with increasing complexity of the reference states [15][16][17][18][19][20][21] .…”

Section: Introductionmentioning

confidence: 99%

Automated Fitting of Neural Network Potentials at Coupled Cluster Accuracy: Protonated Water Clusters as Testing Ground

Schran

Behler

Marx

2019

J. Chem. Theory Comput.

118

137

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Highly accurate potential energy surfaces are of key interest for the detailed understanding and predictive modeling of chemical systems. In recent years, several new types of force fields, which are based on machine learning algorithms and fitted to ab initio reference calculations, have been introduced to meet this requirement. Here we show how high-dimensional neural network potentials can be employed to automatically generate the potential energy surface of finite sized clusters at coupled cluster accuracy, namely CCSD(T*)-F12a/aug-cc-pVTZ. The developed automated procedure utilizes the established intrinsic properties of the model such that the configurations for the training set are selected in an unbiased and efficient way to minimize the computational effort of expensive reference calculations. These ideas are applied to protonated water clusters from the hydronium cation, H 3 O + , up to the tetramer, H 9 O + 4 , and lead to a common potential energy surface that describes all these systems at essentially converged coupled cluster accuracy with a fitting error of 0.06 kJ/mol per atom. The fit is validated in detail and separately for all clusters up to the tetramer and yields reliable results not only for stationary points, but also for reaction pathways, intermediate configurations, as well as different sampling techniques. Per design the NNPs constructed in this fashion can handle very different conditions including the quantum nature of the nuclei and enhanced sampling techniques covering very low as well as high temperatures. This enables fast and exhaustive exploration of the targeted protonated water clusters at essentially converged interactions. In addition, the automated process will allow one to tackle finite systems much beyond the present case.

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Section: Introductionmentioning

confidence: 99%

Automated Fitting of Neural Network Potentials at Coupled Cluster Accuracy: Protonated Water Clusters as Testing Ground

Schran

Behler

Marx

2019

J. Chem. Theory Comput.

118

137

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“…For H 5 O + 2 (see Table S5) MS-MMPT-MP2 force field calculations yield results close to those from the reference MP2/6-311+G(2d,2p) calculations (and therefore to CCSD(T)-F12/aVTZ) except for one of the bending vibrations which are described by harmonic potentials. 51 Overall, results from the MS-MMPT-IR force field (red symbols in Figure 6 Tables S2 and S3) and is therefore computationally considerably more effective.…”

Section: Improved Parametrization Based On Infrared Spectroscopymentioning

confidence: 96%

“…Comparison of harmonic frequencies for OH stretches and HOH bends between the MS-MMPT-MP2 force field (x-axis, black) and the MS-MMPT-IR force field (red), respectively, and calculations at the CCSD(T)-F12/aVTZ level of theory (y-axis)51 at the minimum energy conformations for [H 2 O] 2 H + (Zundel, circle), [H 2 O] 3 H + (triangle), and [H 2 O] 4 H + (Eigen, square) structures.Normal Modes: Although the primary aim of the present work is to introduce a computationally efficient model to follow proton dislocation in liquid water, it is instructive to compare normal mode frequencies with results from reference CCSD(T)-F12/aVTZ calculations for [H 2 O] n H + (n = 2, 3, 4). 51 However, no direct comparison with experiment should be made due to the harmonic approximation used.…”

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confidence: 99%

Multistate Reactive Molecular Dynamics Simulations of Proton Diffusion in Water Clusters and in the Bulk

Meuwly

2019

J. Phys. Chem. B

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The molecular mechanics with proton transfer (MMPT) force field is combined with multi state adiabatic reactive molecular dynamics (MS-ARMD) to describe proton transport in the condensed phase. Parametrization for small protonated water clusters based on electronic structure calculations at the MP2/6-311+G(2d,2p) level of theory and refinement by comparing with infrared spectra for protonated water tetramer yields a force field which faithfully describes minimum energy structures of small protonated water clusters. In protonated water clusters up to (H 2 O) 100 H + the proton hopping rate is around 100 hops/ns. Convergence of such rates is already found for 21 ≤ n ≤ 31 and no further speedup in bulk water is found. This indicates that bulk-like behaviour requires solvation of a Zundel motif by ∼ 25 water molecules which corresponds to the second solvation sphere. For smaller cluster sizes the number of available states, i.e. the number of proton acceptors, is too small and slows down proton transfer * To whom correspondence should be addressed 1 rates. The cluster simulations confirm that the excess proton is typically located on the surface. The free energy surface as a function of the weights of the two lowest states and a configurational parameter suggest that the "special pair" plays a central role in rapid proton transport. The barriers between this minimum energy structure and the Zundel and Eigen minima are sufficiently low (∼ 1 kcal/mol, consistent with recent experiments and commensurate with a hopping rate of ∼ 100/ns or 1 every 10 ps) which lead to a highly dynamical environment. These findings are also consistent with recent experiments which find that Zundel-type hydration geometries are prevalent in bulk water.2

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“…In the present case, the potential energy and dipole surfaces were made available to us in the form of a numerical library by Joel Bowman and coworkers. 24,25 The potential and dipole routines take a single coordinate vector as input and return the respective energy value or 3component dipole vector.…”

Section: Sum-of-products Of Potential and Dipole Moment Surfacesmentioning

confidence: 99%

The coupling of the hydrated proton to its first solvation shell

Schröder¹,

Gatti²,

Lauvergnat³

et al. 2022

Preprint

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Benchmark Electronic Structure Calculations for H₃O⁺(H₂O)_n, n = 0–5, Clusters and Tests of an Existing 1,2,3-Body Potential Energy Surface with a New 4-Body Correction

Cited by 41 publications

References 64 publications

Automated Fitting of Neural Network Potentials at Coupled Cluster Accuracy: Protonated Water Clusters as Testing Ground

Automated Fitting of Neural Network Potentials at Coupled Cluster Accuracy: Protonated Water Clusters as Testing Ground

Multistate Reactive Molecular Dynamics Simulations of Proton Diffusion in Water Clusters and in the Bulk

The coupling of the hydrated proton to its first solvation shell

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