Role of dipolar correlations in the infrared spectra of water and ice

Chen, Wei; Sharma, Manu; Resta, Raffaele; Galli, Giulia; Car, Roberto

doi:10.1103/physrevb.77.245114

Cited by 76 publications

(109 citation statements)

References 32 publications

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“…2A upon integration along the correlation distance r. In the decomposed spectrum the positive auto-correlations seen for about r < 1 Å are found to dominate the IR spec- trum at all frequencies, whereas distinct frequency-dependent cross-correlations are observed beyond. Motions of the nearestneighbors up to r ≈ 3.5 Å around a given water molecule at r ¼ 0 Å induce dipole cross-correlations within the first solvation shell in qualitative accord with earlier observations (31). Note that the computed center-of-mass radial distribution function g com ðrÞ has its first intermolecular maximum and minimum at r ≈ 2.7 Å and ≈3.3 Å, respectively, and a second maximum at ≈4.4 Å.…”

Section: Resultssupporting

confidence: 74%

“…The corresponding spectral densities of these modes, I S γ ðωÞ ¼ ∫ dt exp½−iωt h _ S γ ð0Þ _ S γ ðtÞi, are obtained as usual from the mode velocities, _ S γ . Note that these procedures are related in spirit to, but clearly different from, earlier analysis techniques (29)(30)(31).…”

Section: Methodology: Spatial Decompositions Of Ir Spectramentioning

confidence: 99%

“…In contrast, pioneering ab initio MD (AIMD) simulations of the IR spectrum of heavy water (29) were able to reproduce the 200 cm −1 feature and assigned this to antisymmetric HB stretching modes. This discrepancy in the IR absorption cross section obtained from (polarizable) force fields versus AIMD studies has been explained (30,31) in terms of intermolecular charge fluctuations in locally tetrahedral HB environments. These studies thus underline the collective character of low-frequency modes in conjunction with electronic polarization effects beyond single molecules (30,31).…”

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confidence: 99%

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Dissecting the THz spectrum of liquid water from first principles via correlations in time and space

Heyden

Sun

Funkner

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

410

490

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Solvation of molecules in water is at the heart of a myriad of molecular phenomena and of crucial importance to understanding such diverse issues as chemical reactivity or biomolecular function. Complementing well-established approaches, it has been shown that laser spectroscopy in the THz frequency domain offers new insights into hydration from small solutes to proteins. Upon introducing spatially-resolved analyses of the absorption cross section by simulations, the sensitivity of THz spectroscopy is traced back to characteristic distance-dependent modulations of absorption intensities for bulk water. The prominent peak at ≈200 cm -1 is dominated by first-shell dynamics, whereas a concerted motion involving the second solvation shell contributes most significantly to the absorption at about 80 cm -1 ≈2.4 THz. The latter can be understood in terms of an umbrella-like motion of two hydrogen-bonded tetrahedra along the connecting hydrogen bond axis. Thus, a modification of the hydrogen bond network, e.g., due to the presence of a solute, is expected to affect vibrational motion and THz absorption intensity at least on a length scale that corresponds to two layers of solvating water molecules. This result provides a molecular mechanism explaining the experimentally determined sensitivity of absorption changes in the THz domain in terms of distinct, solute-induced dynamical properties in solvation shells of (bio)molecules—even in the absence of well-defined resonances.

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Section: Resultssupporting

confidence: 74%

Section: Methodology: Spatial Decompositions Of Ir Spectramentioning

confidence: 99%

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confidence: 99%

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Dissecting the THz spectrum of liquid water from first principles via correlations in time and space

Heyden

Sun

Funkner

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

410

490

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“…In the absence of absorption spectra for acetonitrile below 700 cm −1 , it is presently unclear whether its absorbed radiance for the total IR range is also significantly lower (than for the protic solvents). Nonetheless, given the prominent role of hydrogen-bonding in low-frequency modes of protic liquids,[38] as well as band broadening effects, it seems reasonable to hypothesize that protic solvents like water and methanol absorb blackbody radiation more efficiently (at these particular temperatures) than acetonitrile. Assuming this hypothesis is correct, this might in fact explain some of our experimental results more convincingly.…”

Section: Resultsmentioning

confidence: 99%

Effects of ESI conditions on kinetic trapping of the solution-phase protonation isomer of p-aminobenzoic acid in the gas phase

Patrick

Cismesia

Tesler

et al. 2017

International Journal of Mass Spectrometry

125

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The effects of electrospray ionization (ESI) solvent and source temperature on the relative abundance of the preferred solution-phase (N-protonated; i.e. amine) versus preferred gas-phase (O-protonated; i.e., acid) isomers of p-aminobenzoic acid (PABA) were investigated. When PABA was electrosprayed from protic solvents (i.e., methanol/water), the infrared multiple photon dissociation (IRMPD) spectrum recorded was consistent with that for O-protonation, according to both calculations and previous studies. When aprotic solvent (i.e., acetonitrile) was used, a different spectrum was recorded and was assigned to the N-protonated isomer. As the amine is the preferred protonation site in solution, this suggests that an isomerization takes place under certain conditions. Photodissociation at the diagnostic band for the O-protonated isomer (NH2 stretching mode) was used to quantify the relative contributions of each isomer to ion signal as a function of ESI conditions. For mixtures of methanol and acetonitrile, the relative contribution of the O-protonated gas-phase structure increased as a function of methanol content. Yet, substituting methanol for water resulted in a marked decrease of isomerization to the O-protonated structure. The source temperature (i.e., temperature of a heated desolvation capillary) was found to play a key role in determining the extent of isomerization, with higher temperatures yielding increased presence of gas-phase structures. These results are consistent with a protic bridge mechanism, in which the ESI droplet temperatures, dependent on endothermic desolvation and radiative heating from the capillary, may determine the isomerization yield.

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“…The AIMD-VACF approach naturally include finite-temperature anharmonic effects missing in the Hessian-harmonic approximation, but it does not produce accurate IR intensities (for which an autocorrelation function based on the exact dipole moments would be needed [61][62][63]). Despite these issues, it turns out that, in the case of 45S5 Bioglass , the two methods give similar frequencies of the individual modes [53].…”

Section: Structural Propertiesmentioning

confidence: 99%

Rationalizing the Biodegradation of Glasses for Biomedical Applications Through Classical and Ab-initio Simulations

Tilocca

2015

Molecular Dynamics Simulations of Disordered Materials

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The gradual dissolution of a glass in a living host determines the rate at which processes leading to tissue regeneration can occur, which is of crucial importance for the success of biomedical implants and scaffolds for tissue engineering based on the glass. In-situ radiotherapy applications are also affected-in an opposite way-by the rate at which the glass vector used to deliver radioisotopes will degrade in the bloodstream. This chapter illustrates how a combination of classical and ab-initio simulations techniques, mainly centred on Molecular Dynamics, can shed new light into structural and dynamical features that control the biodegradation of these materials. IntroductionA biomaterial is a material able to elicit a favourable reaction from the human body, leading for instance to the repair of damaged or diseased tissues, including but not limited to bones and soft tissues [1,2]. The high costs and risks associated to autoand allografts for bone replacement have led to large advances in the development and clinical application of synthetic substitutes. For instance, first-generation bioinert materials are metals, alloys and ceramics such as zirconia and alumina, whose application as bone replacement relies on a tight mechanical fit in the implant site. A superior performance can be achieved by second-generation bioactive materials, able to form chemical bonds with the existing issues, which results in better biocompatibility, integration and stability of the implant [1]. The first biomaterials with these desirable bone-bonding properties were the soda-lime phosphosilicate compositions (such as the 45S5 Bioglass ) introduced by Hench in the 70s [3]. Even though several other bioactive materials (such as crystalline calcium phosphates and silicates [4]) able to bond to tissues have been identified thereafter, their performances have A.Tilocca (B)

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Role of dipolar correlations in the infrared spectra of water and ice

Cited by 76 publications

References 32 publications

Dissecting the THz spectrum of liquid water from first principles via correlations in time and space

Dissecting the THz spectrum of liquid water from first principles via correlations in time and space

Effects of ESI conditions on kinetic trapping of the solution-phase protonation isomer of p-aminobenzoic acid in the gas phase

Rationalizing the Biodegradation of Glasses for Biomedical Applications Through Classical and Ab-initio Simulations

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