Confinement of hydrogen and hydroxyl radicals in water cages: a density functional theory study

Liu, Liuxie; Mao, Shuang; Li, Quan; Wang, Xiaolan; Yang, Mingli; Li, Laicai

doi:10.1039/c6ra28804a

Cited by 6 publications

(4 citation statements)

References 69 publications

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“…[31] The most popular hybrid functional has successfully demonstrated that the OH radical is encapsulated in water cages. [64] One important aim of the current study is to investigate the trend of the OH ⋆ stretching vibration from the gas phase up to liquid water because the currently only available MD simulation reveals only a band position from a power spectrum of one OH radical in liquid water. [24] A second aim is to examine the OH ⋆ stretching vibration of the OH radical in water clusters by using two different methods, namely the MLWF scheme and the radical Voronoi tessellation.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Spectra of the OH Radical in Water: Ab Initio Molecular Dynamics Simulations and Quantum Chemical Calculations Using Hybrid Functionals

Apostolidou

2020

Advcd Theory and Sims

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The OH radical has remarkable features in aqueous environments. Studies of vibrational properties can uncover more information about this omnipresent radical. However, infrared spectra of the OH radical in water represent a challenging task. This work studies the OH ⋆ stretching vibration from the gas phase for OH ⋆-wn (w = water, n = 0-5) clusters to the bulk phase for OH ⋆-w31 via ab initio molecular dynamics (AIMD) simulations with B3LYP-D3 and the maximally localized Wannier function scheme. The infrared spectrum of pure liquid water reveals from an AIMD simulation with 32 water molecules a characteristic bulk phase. The OH ⋆ stretching vibration is continuously red-shifted from the gas phase to liquid water. This fact is supported by static DFT and RI-MP2 calculations. A comparison of Wannier and radical Voronoi tessellation spectra leads to the same result for all clusters, which implies the absence of delocalized electrons. Despite the use of van der Waals radii, the Voronoi approach is able to distinguish between strong and weak hydrogen bonds, emphasizing the flexibility of this approach toward different hydrogen bond types. The stretching vibration of the OH ⋆ in the gas phase appears as a doublet due to the coupling of rotation and stretching.

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Section: Introductionmentioning

confidence: 99%

Vibrational Spectra of the OH Radical in Water: Ab Initio Molecular Dynamics Simulations and Quantum Chemical Calculations Using Hybrid Functionals

Apostolidou

2020

Advcd Theory and Sims

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“…Therefore, it is of advantage to use dispersion corrected hybrid functionals, if liquid water is used in an AIMD simulation. [166][167][168][169] Regarding open-shell systems, it could be successfully shown in 2017 by Liu et al, 410 using DFT-D3 calculations, that hydroxyl radicals are encapsulated in water cages. Furthermore, a benchmark study of Tentscher and Arey, 411 about binding in radical-solvent binary complexes, revealed that the dispersion correction has a minor impact on their results.…”

Section: Introductionmentioning

confidence: 99%

“…41 The most popular hybrid functional has successfully demonstrated that the OH radical is encapsulated in water cages. 410 One important aim of the current study is to investigate the trend of the OH stretching vibration from the gas phase up to liquid water because the currently only available MD simulation reveals only a band position from a power spectrum of one OH radical in liquid water. 90 A second aim is to examine the OH stretching vibration of the OH radical in water clusters by using two different methods, namely the MLWF scheme and the radical Voronoi tessellation.…”

Section: Introductionmentioning

confidence: 99%

OH radical in water from ab initio molecular dynamics simulation employing hybrid functionals

Apostolidou

2019

The Journal of Chemical Physics

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In this thesis, complicated solvation phenomena that are impossible to observe via laboratory experiments are comprehensively investigated by molecular dynamics (MD) simulations. The studied system types are the OH radical in aqueous systems and keratin in ionic liquids (ILs), which are both important key contributors to the environment. The OH radical effectively cleanses the atmosphere and is also used in wastewater cleaning processes. Regenerated keratin is a biodegradable material that has been recently used as an ingredient in bioplastics. Its regeneration minimizes environmental pollution and a regeneration process by means of a greener route with ILs underpins the urgency of this research area.Within the last 15 years, only representative ab initio MD (AIMD) simulation studies with the generalized gradient approximation (GGA) functionals can be found for the OH radical in aqueous environments. However, these aforementioned functionals include the self-interaction error (SIE) that leads to artificial delocalization of unpaired electrons. Thus, a comprehensive, representative and accurate Born-Oppenheimer (BO) MD simulation study of OH -wn (w=water, n=1-5) clusters and OH -w31 was performed by employing hybrid functionals and the accurate diffuse basis set DZVP-MOLOPT-SR-GTH. In particular, one important research area was to investigate the existence of the hemibonded structure. This hemibonded structure is a threeelectron two-center interaction between the oxygen atoms of the OH radical and water with a characteristic low O -O distance of around 238 pm and a delocalization of the unpaired electron over these two centers. With the aid of this highly accurate BOMD simulation, the absence of the long-debated hemibonded configuration is shown. This clearly conveys that the hemibonded structure is an artifact from the SIE. Furthermore, this thesis reveals that a less accurate basis set such as the 6-31G basis set and a too low simulation temperature can also lead to the occurrence of the hemibonded structure. Since these two features were also used in recent AIMD simulation studies, this thesis paves the way for a more accurate description of this system type and thus sets a clear milestone within the whole topic. Finally, also the orientation of the OH radical in the gas phase up to bulk liquid water was studied by means of these BOMD simulations. It is shown that the OH radical has a less propensity for the bulk phase and that the highest occurrence is given by the OH -w1 complex in which the OH acts as a hydrogen bond donor toward water and which will therefore be a focal point for future tropospheric reactions.Additionally, a BOMD simulation of pure liquid water, involving 32 water molecules and simulated at the B3LYP-D3 and PBE0-TC-LRC-D3 levels of theory, showed very precise structural features that were in very good agreement with highly accurate experimental data.The former BOMD simulations of the OH radical in aqueous systems by using the B3LYP-D3/DZVP-MOLOPT-SR-GTH level of theory were further used to ...

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“…3. Both atomic radicals are stable indefinitely at 77 K, remaining trapped at some well-defined site within the hydrate structure (perhaps within empty 5 12 cages 65 ) as evidenced by a super-hyperfine interaction (Fig. 3).…”

Section: Nonlinear Photochemical Responsementioning

confidence: 99%

Two-photon chemistry of tetrahydrofuran in clathrate hydrates

Michon,

Chmielniak,

Weber

et al. 2024

Phys. Chem. Chem. Phys.

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Confinement of hydrogen and hydroxyl radicals in water cages: a density functional theory study

Abstract: Radicals can be confined in water cages and exhibit similar structures and properties to their corresponding free forms.

Cited by 6 publications

References 69 publications

Vibrational Spectra of the OH Radical in Water: Ab Initio Molecular Dynamics Simulations and Quantum Chemical Calculations Using Hybrid Functionals

Vibrational Spectra of the OH Radical in Water: Ab Initio Molecular Dynamics Simulations and Quantum Chemical Calculations Using Hybrid Functionals

OH radical in water from ab initio molecular dynamics simulation employing hybrid functionals

Two-photon chemistry of tetrahydrofuran in clathrate hydrates

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