Optimal geometries and harmonic vibrational frequencies of the global minima of water clusters (H2O)<i>n</i>, <i>n</i> = 2–6, and several hexamer local minima at the CCSD(T) level of theory

Miliordos, Evangelos; Aprà, Edoardo; Xantheas, Sotiris S.

doi:10.1063/1.4820448

Cited by 112 publications

(134 citation statements)

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“…It should be noted that the analogous slope for the weaker water−water bonds in neutral water clusters is significantly smaller at 200 cm −1 /0.01 Å. 102 We also note that the relationship between frequency shift and electric field-induced bond length of both H 2 O and OH − has similarly been found to be linear, 105,106 with a smaller slope (160 cm −1 /0.01 Å) compared to that observed here for the hydronium ion.…”

Section: Feature Articlementioning

confidence: 97%

“…An analogous linear correlation between the bond lengths of the hydrogen bonded OH stretches and the corresponding red shifts for neutral water clusters up to the hexamer has been demonstrated by Xantheas and Dunning 101 at the MP2 and recently by Miliordos and Xantheas 102 at the CCSD(T) levels of theory, in accordance to Badger's rule. 102,103 According to that rule, originally proposed by Badger for the first and second row diatomic molecules and subsequently extended to incorporate the hydrogen bonded OH stretches, 104 the lengthening/shortening of the OH bond encodes the corresponding red/blue frequency shift. The shortest calculated bond (the nonbonded hydronium in n = 3) does, in fact, yield the most blue-shifted stretch at 3670 cm −1 , which falls between the symmetric and asymmetric OH stretches of the neutral solvating water molecules.…”

Section: Feature Articlementioning

confidence: 98%

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Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H⁺(H₂O)_n=2–28 Clusters

et al. 2015

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We review the role that gas-phase, size-selected protonated water clusters, H(+)(H2O)n, have played in unraveling the microscopic mechanics responsible for the spectroscopic behavior of the excess proton in bulk water. Because the larger (n ≥ 10) assemblies are formed with three-dimensional cage morphologies that more closely mimic the bulk environment, we report the spectra of cryogenically cooled (10 K) clusters over the size range 2 ≤ n ≤ 28, over which the structures evolve from two-dimensional arrangements to cages at around n = 10. The clusters that feature a complete second solvation shell around a surface-embedded hydronium ion yield spectral signatures of the proton defect similar to those observed in dilute acids. The origins of the large observed shifts in the proton vibrational signature upon cluster growth were explored with two types of theoretical analyses. First, we calculate the cubic and semidiagonal quartic force constants and use these in vibrational perturbation theory calculations to establish the couplings responsible for the large anharmonic red shifts. We then investigate how the extended electronic wave functions that are responsible for the shapes of the potential surfaces depend on the nature of the H-bonded networks surrounding the charge defect. These considerations indicate that, in addition to the sizable anharmonic couplings, the position of the OH stretch most associated with the excess proton can be traced to large increases in the electric fields exerted on the embedded hydronium ion upon formation of the first and second solvation shells. The correlation between the underlying local structure and the observed spectral features is quantified using a model based on Badger's rule as well as via the examination of the electric fields obtained from electronic structure calculations.

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Section: Feature Articlementioning

confidence: 97%

Section: Feature Articlementioning

confidence: 98%

Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H⁺(H₂O)_n=2–28 Clusters

et al. 2015

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“…Different (H 2 O) 6 isomers were identified for the water hexamer: the tridimensional prism, cage and book are almost isoenergetic, whereas the cyclic isomer is slightly higher in energy [46,47].The MESPs of each of these isomers are presented in Figure 3. One face of the prism isomer presents a similar MESP to the one of the uudd water tetramer, with two consecutive electron-rich regions followed by two consecutive electron-deficient regions.…”

Section: Bpl:(h 2 O) 6 Complexmentioning

confidence: 99%

A theoretical investigation of water–solute interactions: from facial parallel to guest–host structures

2017

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Encapsulation of small (bio-)organic molecules within water cages is governed by a subtle equilibrium between water-water and water-solute interactions. The competition between the formation of exohedral and endohedral complexes is investigated. The first step prior to a theoretical characterization of interactions involved in such complexes lies in the judicious choice of a level of theory. The β-propiolactone (BPL), a solute for which the micro-hydration was recently characterized by means of high resolution microwave spectroscopy (Angew. Chem. 2015, 127, 993), was selected for the present study, and a calibration step is carried out. It is shown that the dispersion-corrected density functional theory (DFT-D) suitably reproduce the geometric, energetic and spectroscopic features of the BPL:(H 2 O) 1-5 complexes. The experimentally-deduced structures of the BPL:(H 2 O) 4,5 species are fully understood in terms of the maximization of interactions between complementary sites in the MESPs. DFT-D calculations followed by the topological analysis within the Quantum Theory of Atoms in Molecules framework have shown that the solute could efficiently interact with (H 2 O) 6,10 clusters in a similar manner that the (H 2 O) 4,5 clusters do. The interaction of the solute with two larger water clusters is further investigated. The exohedral and endohedral BPL:(H 2 O) 20 isomers are close in energy with each other, whereas the formation of an inclusion complex is energetically more favored than the facial interaction in the case of the BPL:(H 2 O) 24 cluster. The topological analysis suggests that the substantial energetic stability is due to interactions between the solute and almost all oxygen atoms of the water cage.

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“…3 Several studies, reporting the theoretically calculated vibrational spectra of a variety of molecular clusters, are available in the literature. [4][5][6][7][8][9][10][11][12][13] Among these, most of the investigations are reported on water clusters. Xantheas and coworkers [4][5][6][7] have explored the energetics and vibrational spectra of water clusters of various sizes, during the last decade.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11][12][13] Among these, most of the investigations are reported on water clusters. Xantheas and coworkers [4][5][6][7] have explored the energetics and vibrational spectra of water clusters of various sizes, during the last decade. Vibrational signatures of different hydrogen bond (HB) networks of small-sized (H 2 O) 6 to large-sized (H 2 O) 20 clusters have been analyzed at Møller-Plesset second order (MP2) level of theory.…”

Section: Introductionmentioning

confidence: 99%

Accurate vibrational spectra via molecular tailoring approach: A case study of water clusters at MP2 level

Sahu

Gadre

2015

The Journal of Chemical Physics

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In spite of the recent advents in parallel algorithms and computer hardware, high-level calculation of vibrational spectra of large molecules is still an uphill task. To overcome this, significant effort has been devoted to the development of new algorithms based on fragmentation methods. The present work provides the details of an efficient and accurate procedure for computing the vibrational spectra of large clusters employing molecular tailoring approach (MTA). The errors in the Hessian matrix elements and dipole derivatives arising due to the approximation nature of MTA are reduced by grafting the corrections from a smaller basis set. The algorithm has been tested out for obtaining vibrational spectra of neutral and charged water clusters at Møller-Plesset second order level of theory, and benchmarking them against the respective full calculation (FC) and/or experimental results. For (H2O)16 clusters, the estimated vibrational frequencies are found to differ by a maximum of 2 cm(-1) with reference to the corresponding FC values. Unlike the FC, the MTA-based calculations including grafting procedure can be performed on a limited hardware, yet take a fraction of the FC time. The present methodology, thus, opens a possibility of the accurate estimation of the vibrational spectra of large molecular systems, which is otherwise impossible or formidable.

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Optimal geometries and harmonic vibrational frequencies of the global minima of water clusters (H2O)n, n = 2–6, and several hexamer local minima at the CCSD(T) level of theory

Cited by 112 publications

References 105 publications

Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H⁺(H₂O)_n=2–28 Clusters

Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H⁺(H₂O)_n=2–28 Clusters

A theoretical investigation of water–solute interactions: from facial parallel to guest–host structures

Accurate vibrational spectra via molecular tailoring approach: A case study of water clusters at MP2 level

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Optimal geometries and harmonic vibrational frequencies of the global minima of water clusters (H2O)n, n = 2–6, and several hexamer local minima at the CCSD(T) level of theory

Cited by 112 publications

References 105 publications

Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H+(H2O)n=2–28 Clusters

Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H+(H2O)n=2–28 Clusters

A theoretical investigation of water–solute interactions: from facial parallel to guest–host structures

Accurate vibrational spectra via molecular tailoring approach: A case study of water clusters at MP2 level

Contact Info

Product

Resources

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Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H⁺(H₂O)_n=2–28 Clusters

Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H⁺(H₂O)_n=2–28 Clusters