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Tetrahedral structure of supercooled water at ambient pressure and its influence on dynamic relaxation: Comparative study of water models. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117269] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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3
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Sha M, Yamada SA, Fayer MD. Orientational Pair Correlations and Local Structure of Benzonitrile from Molecular Dynamics Simulations with Comparisons to Experiments. J Phys Chem B 2021; 125:3163-3177. [PMID: 33730488 DOI: 10.1021/acs.jpcb.0c11148] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present an experimentally parametrized molecular dynamics study of single-molecule and collective orientational relaxation in neat benzonitrile through the analysis of the reorientational anisotropy and polarizability anisotropy time correlation function (PA-TCF). The simulations show that the PA-TCF is dominated by collective reorientation after 20 ps. Collective reorientation is found to be slower than single-molecule reorientation by a factor of 1.67, consistent with recent experiments. The simulations provide direct evidence of local antiparallel benzonitrile configurations. These structures, which have been the center of some debate, are responsible for the slower rate of collective versus single-molecule reorientation in the liquid. Further structural analysis indicates that significant Coulombic interactions between the nitrile group and hydrogen atoms on adjacent molecules play a role in the formation of the antiparallel structures. The single-molecule dynamics reflected in the anisotropy are complex and consist of a ballistic regime, restricted angular diffusion, and spatially anisotropic free diffusion. The principal components of the rotational diffusion tensor are independently obtained and shown to reproduce the free diffusion regime of the anisotropy for each principal axis according to the predictions of a previous theory.
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Affiliation(s)
- Maolin Sha
- Department of Physics and Materials Engineering, Hefei Normal University, Hefei 230061, China
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Steven A Yamada
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Michael D Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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4
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Tang PH, Wu TM. Molecular dynamics simulations for optical Kerr effect of TIP4P/2005 water in liquid and supercooled states. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.07.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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Perticaroli S, Comez L, Sassi P, Morresi A, Fioretto D, Paolantoni M. Water-like Behavior of Formamide: Jump Reorientation Probed by Extended Depolarized Light Scattering. J Phys Chem Lett 2018; 9:120-125. [PMID: 29243934 DOI: 10.1021/acs.jpclett.7b02943] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Water is a strong self-associated liquid with peculiar properties that crucially depend on H-bonding. As regards its molecular dynamics, only recently has water reorientation been successfully described based on a jump mechanism, which is responsible for the overall H-bonding exchange. Here, using high-resolution broad-band depolarized light scattering, we have investigated the reorientational dynamics of formamide (FA) as a function of concentration from the neat liquid to diluted aqueous solutions. Our main findings indicate that in the diluted regime the water rearrangement can trigger the motion of FA solute molecules, which are forced to reorient at the same rate as water. This highlights an exceptional behavior of FA, which perfectly substitutes water within its network. Besides other fundamental implications connected with the relevance of FA, its water-like behavior provides rare experimental evidence of a solute whose dynamics is completely slaved to the solvent.
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Affiliation(s)
- S Perticaroli
- Shull Wollan Center, a Joint Institute for Neutron Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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6
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Bender JS, Fourkas JT, Coasne B. Empirical Analysis of Optical Kerr Effect Spectra: A Case for Constraint. J Phys Chem B 2017; 121:11376-11382. [PMID: 29161049 DOI: 10.1021/acs.jpcb.7b09751] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ultrafast optical Kerr effect (OKE) spectroscopy is a widely used method for studying the depolarized, Raman-active intermolecular dynamics of liquids. Through appropriate manipulation of OKE data, it is possible to determine the reduced spectral density (RSD), which is the Bose-Einstein-corrected, low-frequency Raman spectrum with the contribution of diffusive reorientation removed. OKE RSDs for van der Waals liquids can often be fit well to an empirical function that is the sum of a Bucaro-Litovitz function and an antisymmetrized Gaussian (AG). Although these functions are not directly representative of specific intermolecular dynamics, the AG fit parameters can provide useful insights into the microscopic properties of liquids. Here we show that fits using the AG function are typically not well-determined, and that equally good results can be obtained with a wide range of fitting parameters. We propose the use of a physically motivated constraint on the amplitude of the AG function, and demonstrate that this constraint leads to more intuitive trends in the fit parameters for temperature-dependent RSDs in 1,3,5-trifluorobenzene and hexafluorobenzene.
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Affiliation(s)
| | | | - Benoit Coasne
- Université Grenoble Alpes, CNRS, LIPhy , 38000 Grenoble, France
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7
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Hu NY, Lin K, Zhou XG, Liu SL. Populations of Ethanol Conformers in Liquid CCl4 and CS2 by Raman Spectra in OH Stretching Region. CHINESE J CHEM PHYS 2015. [DOI: 10.1063/1674-0068/28/cjcp1503048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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8
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Taschin A, Bartolini P, Eramo R, Righini R, Torre R. Optical Kerr effect of liquid and supercooled water: the experimental and data analysis perspective. J Chem Phys 2015; 141:084507. [PMID: 25173021 DOI: 10.1063/1.4893557] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful experimental tool enabling accurate investigations of the dynamic phenomena in molecular liquids. We introduced innovative experimental and fitting procedures, that enable a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of liquid water. We report OKE data on water measuring intermolecular vibrations and the structural relaxation processes in an extended temperature range, inclusive of the supercooled states. The unpreceded data quality makes possible a solid comparison with few theoretical models: the multi-mode Brownian oscillator model, the Kubo's discrete random jump model, and the schematic mode-coupling model. All these models produce reasonable good fits of the OKE data of stable liquid water, i.e., over the freezing point. The features of water dynamics in the OKE data becomes unambiguous only at lower temperatures, i.e., for water in the metastable supercooled phase. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if its intrinsic hydrodynamic approach does not give a direct access to the molecular information.
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Affiliation(s)
- A Taschin
- European Lab. for Non-Linear Spectroscopy (LENS), Univ. di Firenze, via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy
| | - P Bartolini
- European Lab. for Non-Linear Spectroscopy (LENS), Univ. di Firenze, via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy
| | - R Eramo
- European Lab. for Non-Linear Spectroscopy (LENS), Univ. di Firenze, via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy
| | - R Righini
- European Lab. for Non-Linear Spectroscopy (LENS), Univ. di Firenze, via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy
| | - R Torre
- European Lab. for Non-Linear Spectroscopy (LENS), Univ. di Firenze, via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy
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9
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Bender JS, Coasne B, Fourkas JT. Assessing Polarizability Models for the Simulation of Low-Frequency Raman Spectra of Benzene. J Phys Chem B 2014; 119:9345-58. [DOI: 10.1021/jp509968v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- John S. Bender
- Department of Chemistry & Biochemistry, ‡Institute for Physical Science and Technology, §Maryland NanoCenter, and ∥Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, United States
- Multiscale Materials Science for Energy and Environment, UMI 3466
CNRS-MIT, and #Department
of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachussetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Benoit Coasne
- Department of Chemistry & Biochemistry, ‡Institute for Physical Science and Technology, §Maryland NanoCenter, and ∥Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, United States
- Multiscale Materials Science for Energy and Environment, UMI 3466
CNRS-MIT, and #Department
of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachussetts Avenue, Cambridge, Massachusetts 02139, United States
| | - John T. Fourkas
- Department of Chemistry & Biochemistry, ‡Institute for Physical Science and Technology, §Maryland NanoCenter, and ∥Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, United States
- Multiscale Materials Science for Energy and Environment, UMI 3466
CNRS-MIT, and #Department
of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachussetts Avenue, Cambridge, Massachusetts 02139, United States
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10
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Milischuk AA, Ladanyi BM. Polarizability anisotropy relaxation in nanoconfinement: Molecular simulation study of water in cylindrical silica pores. J Chem Phys 2014; 141:18C513. [DOI: 10.1063/1.4896218] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Anatoli A. Milischuk
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Branka M. Ladanyi
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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11
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Sun X, Ladanyi BM, Stratt RM. Effects of Electronic-State-Dependent Solute Polarizability: Application to Solute-Pump/Solvent-Probe Spectra. J Phys Chem B 2014; 119:9129-39. [DOI: 10.1021/jp509021c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Xiang Sun
- Department
of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Branka M. Ladanyi
- Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
| | - Richard M. Stratt
- Department
of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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12
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Palombo F, Sassi P, Paolantoni M, Barontini C, Morresi A, Giorgini MG. Complex Dynamical Aspects of Organic Electrolyte Solutions. J Phys Chem B 2013; 118:215-25. [DOI: 10.1021/jp4066604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Francesca Palombo
- School of Physics, University of Exeter , EX4 4QF Exeter, United Kingdom
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13
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Sun X, Stratt RM. How a solute-pump/solvent-probe spectroscopy can reveal structural dynamics: Polarizability response spectra as a two-dimensional solvation spectroscopy. J Chem Phys 2013; 139:044506. [DOI: 10.1063/1.4816373] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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14
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Ingrosso F, Ladanyi BM. Intermolecular Structure and Collective Dynamics of Supercritical Fluoroform Studied by Molecular Dynamics Simulations. J Phys Chem B 2013; 117:654-67. [DOI: 10.1021/jp310246v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Francesca Ingrosso
- Theoretical Chemistry and Biochemistry
Group SRSMC UMR 7565, CNRS − Université de Lorraine, Boulevard des Aiguillettes, BP 70239 54506
Vandoeuvre-lès-Nancy Cedex, France
- CNRS, SRSMC, UMR 7565,
Vandoeuvre-lès-Nancy, F-54506, France
| | - Branka M. Ladanyi
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523,
United States
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15
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Lupi L, Comez L, Paolantoni M, Fioretto D, Ladanyi BM. Dynamics of Biological Water: Insights from Molecular Modeling of Light Scattering in Aqueous Trehalose Solutions. J Phys Chem B 2012; 116:7499-508. [DOI: 10.1021/jp301988f] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Laura Lupi
- Dipartimento di
Fisica, Università degli Studi di Perugia, Via Pascoli, I-06123 Perugia, Italy
| | - Lucia Comez
- Dipartimento di
Fisica, Università degli Studi di Perugia, Via Pascoli, I-06123 Perugia, Italy
- IOM-CNR c/o Dipartimento di Fisica, Università di Perugia, Via Pascoli,
I-06123, Perugia, Italy
| | - Marco Paolantoni
- Dipartimento di Chimica, Università di Perugia, via Elce di Sotto, I-06123
Perugia, Italy
| | - Daniele Fioretto
- Dipartimento di
Fisica, Università degli Studi di Perugia, Via Pascoli, I-06123 Perugia, Italy
- Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), Università of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy
| | - Branka M. Ladanyi
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872,
United States
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16
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Sun X, Stratt RM. The molecular underpinnings of a solute-pump/solvent-probe spectroscopy: the theory of polarizability response spectra and an application to preferential solvation. Phys Chem Chem Phys 2012; 14:6320-31. [DOI: 10.1039/c2cp24127g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Sturlaugson AL, Fruchey KS, Lynch SR, Aragón SR, Fayer MD. Orientational and translational dynamics of polyether/water solutions. J Phys Chem B 2010; 114:5350-8. [PMID: 20373773 DOI: 10.1021/jp101369e] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Optical heterodyne-detected optical Kerr effect (OHD-OKE) experiments and pulsed field-gradient spin-echo NMR (PFGSE-NMR) experiments were performed to measure the rotational and translational diffusion constants of a polyether, tetraethylene glycol dimethyl ether (TEGDE), in binary mixtures with water over concentrations ranging from pure TEGDE to approaching infinite dilution. In addition, hydrodynamic calculations of the rotational and translational diffusion constants for several rigid TEGDE conformations in the neat liquid and in the infinitely dilute solution were performed to supplement the experimental data. The rotational relaxation data follow the Debye-Stokes-Einstein (DSE) equation within experimental error over the entire water concentration range. The agreement with the DSE equation indicates that there is no significant structural change of the polyether as the water content is changed. In contrast to the rotational dynamics, the translational diffusion data show a distinct deviation from Stokes-Einstein (SE) behavior. As the water content of the mixture is reduced, the translational diffusion rate decreases less rapidly than the increase in viscosity alone predicts until the water/TEGDE mole ratio of 7:1 is reached. Upon further reduction of water content, the translational diffusion tracks the viscosity. Comparison of the translational data with the rotational data and the hydrodynamic computations shows that the translational dynamics cannot be explained by a molecular shape change and that the low water fraction solutions are the ones that deviate from hydrodynamic behavior. A conjecture is presented as a possible explanation for the different behaviors of the rotational and translational dynamics.
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Affiliation(s)
- Adam L Sturlaugson
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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18
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Yan T, Wang Y, Knox C. On the Dynamics of Ionic Liquids: Comparisons between Electronically Polarizable and Nonpolarizable Models II. J Phys Chem B 2010; 114:6886-904. [DOI: 10.1021/jp908914d] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Tianying Yan
- Institute of New Energy Material Chemistry and Department of Material Chemistry, Nankai University, Tianjin 300071, China, Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 55 East Zhongguancun Road, Beijing, 100190, China, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850
| | - Yanting Wang
- Institute of New Energy Material Chemistry and Department of Material Chemistry, Nankai University, Tianjin 300071, China, Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 55 East Zhongguancun Road, Beijing, 100190, China, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850
| | - Craig Knox
- Institute of New Energy Material Chemistry and Department of Material Chemistry, Nankai University, Tianjin 300071, China, Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 55 East Zhongguancun Road, Beijing, 100190, China, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850
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19
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Hu Z, Huang X, Annapureddy HVR, Margulis CJ. Molecular Dynamics Study of the Temperature-Dependent Optical Kerr Effect Spectra and Intermolecular Dynamics of Room Temperature Ionic Liquid 1-Methoxyethylpyridinium Dicyanoamide. J Phys Chem B 2008; 112:7837-49. [DOI: 10.1021/jp800729g] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhonghan Hu
- Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, and Department of Chemistry, Columbia University, New York, New York 10027
| | - Xuhui Huang
- Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, and Department of Chemistry, Columbia University, New York, New York 10027
| | - Harsha V. R. Annapureddy
- Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, and Department of Chemistry, Columbia University, New York, New York 10027
| | - Claudio J. Margulis
- Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, and Department of Chemistry, Columbia University, New York, New York 10027
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20
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Noskov SY, Lamoureux G, Roux B. Molecular dynamics study of hydration in ethanol-water mixtures using a polarizable force field. J Phys Chem B 2007; 109:6705-13. [PMID: 16851754 DOI: 10.1021/jp045438q] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The abnormal physicochemical characteristics of ethanol solvation in water are commonly attributed to the phenomenon of hydrophobic hydration. To investigate the structural organization of hydrophobic hydration in water-ethanol mixtures, we use molecular dynamics simulations based on detailed atomic models. Induced polarization is incorporated into the potential function on the basis of the classical Drude oscillator model. Water-ethanol mixtures are simulated at 11 ethanol molar fractions, from 0.05 to 0.9. Although the water and ethanol models are parametrized separately to reproduce the vaporization enthalpy, static dielectric constant, and self-diffusion constant of neat liquids at ambient conditions, they also reproduce the energetic and dynamical properties of the mixtures accurately. Furthermore, the calculated dielectric constant for the various water-alcohol mixtures is in excellent agreement with experimental data. The simulations provide a detailed structural characterization of the mixtures. A depletion of water-water hydrogen bonding in the first hydration shell of ethanol is compensated by an enhancement in the second hydration shell. The structuring effect from the second solvation shell gives rise to a net positive hydrogen-bonding excess for ethanol molar fractions up to approximately 0.5. For larger molar fractions, the second hydration shell is not sufficiently populated to overcome the net H-bond depletion from the first shell.
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Affiliation(s)
- Sergei Yu Noskov
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10021, USA
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21
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Elola MD, Ladanyi BM. Molecular Dynamics Study of Polarizability Anisotropy Relaxation in Aromatic Liquids and Its Connection with Local Structure. J Phys Chem B 2006; 110:15525-41. [PMID: 16884276 DOI: 10.1021/jp062071b] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The collective polarizability anisotropy dynamics in a set of three aromatic liquids, benzene (Bz), hexafluorobenzene (HFB), and 1,3,5-trifluorobenzene (TFB), has been studied by molecular dynamics simulation. These liquids have very similar shapes, but different electrostatic interactions due to opposite polarities of C-H and C-F bonds, giving rise to different local intermolecular structures in the liquid phase. We have investigated how these structural arrangements affect polarizability anisotropy dynamics observed in optical Kerr-effect (OKE) spectroscopy. We have modeled the interaction-induced polarizability with the first-order dipole-induced dipole approximation, with the molecular polarizability distributed over the carbon sites. Local contributions to the librational OKE spectrum were computed separately for molecules participating in parallel or perpendicular relative orientations within the first coordination shell. We found that the relative locations of parallel and perpendicular librational bands of the OKE spectra are closely related to the corresponding pair energy distributions of the closest four neighbors of a given molecule, corresponding to a model of a harmonic oscillator in a cage of nearest neighbors. This model predicts higher librational frequencies for more attractive intermolecular interactions, which in all three liquids correspond to parallel local arrangements. On the diffusive orientational time scale, all three liquids exhibit slower relaxation of molecules in parallel arrangements, although the difference in relaxation rates is substantial only in TFB, which has the strongest tendency toward parallel stacking. The analysis of the collective polarizability relaxation was performed using two different approaches, the projection scheme (J. Chem. Phys. 1980, 72, 2801) and the theory developed by Steele (Mol. Phys. 1987, 61, 1031) for the second time derivatives applied to collective time correlations. Both approaches allow the decomposition of the OKE response into contributions from orientational relaxation and other dynamical processes. We find that they lead to different predictions on how the response depends on collective reorientation and processes arising from fluctuations in the interaction-induced polarizability. We discuss the reasons for these differences and the advantages and disadvantages of the two analysis schemes.
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Affiliation(s)
- M Dolores Elola
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
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22
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Tao G, Stratt RM. Why Does the Intermolecular Dynamics of Liquid Biphenyl so Closely Resemble that of Liquid Benzene? Molecular Dynamics Simulation of the Optical-Kerr-Effect Spectra. J Phys Chem B 2005; 110:976-87. [PMID: 16471632 DOI: 10.1021/jp0558932] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The combination of optical-Kerr-effect (OKE) spectroscopy and molecular dynamics simulations has provided us with a newfound ability to delve into the librational dynamics of liquids, revealing, in the process, some surprising commonalities among aromatic liquids. Benzene and biphenyl, for example, have remarkably similar OKE spectra despite marked differences in their shapes, sizes, and moments of inertia--and even more chemically distinct aromatics tend to have noticeable similarities in their spectra. We explore this universality by using a molecular dynamics simulation to investigate the librational dynamics of molten biphenyl and to predict its OKE spectrum, comparing the results with our previous calculations for liquid benzene. We suggest that the impressive level of quantitative agreement between these two liquids is largely a reflection of the fact that librations in these and other aromatic liquids act as torsional oscillations with oscillator frequencies selected from the liquid's librational bands. Since these bands are centered about the librational Einstein frequencies, the quantitative similarities between the liquids are essentially reflections of the near identities of their Einstein frequencies. Why then are the Einstein frequencies themselves so insensitive to molecular details? We show that, for nearly planar molecules, mean-square torques and moments of inertia tend to scale with molecular dimensions in much the same way. We demonstrate that this near cancellation provides both a quantitative explanation of the close relationship between benzene and biphenyl and a more general perspective on the similarities seen in the ultrafast dynamics of aromatic liquids.
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Affiliation(s)
- Guohua Tao
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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23
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Elola MD, Ladanyi BM, Scodinu A, Loughnane BJ, Fourkas JT. Effects of Molecular Association on Polarizability Relaxation in Liquid Mixtures of Benzene and Hexafluorobenzene. J Phys Chem B 2005; 109:24085-99. [PMID: 16375401 DOI: 10.1021/jp054733n] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work we have studied the relaxation dynamics of the many-body polarizability anisotropy in liquid mixtures of benzene (Bz) and hexafluorobenzene (Hf) at room temperature by femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES) experiments and molecular dynamics (MD) simulations. The computed polarizability response arising from intermolecular interactions was included using the first-order dipole-induced-dipole model with the molecular polarizability distributed over the carbon sites of each molecule. We found good qualitative agreement between experiments and simulations in the features exhibited by the nuclear response function R(t) for pure liquids and mixtures. The long-time diffusive decay of R(t) was observed to vary substantially with composition, slowing down noticeably with dilution of each of the species as compared with that in the corresponding pure liquids. MD simulation shows that the effect on R(t) is due to the formation of strong and localized intermolecular association between Bz and Hf species that hinder the rotational diffusive dynamics. The formation of these Bz-Hf complexes in the liquid mixtures also modifies the rotational diffusive dynamics of the component species in such a way that cannot be explained solely in terms of a viscosity effect. Even though the computed orientational diffusive relaxation times associated with Bz and Hf are larger by a factor of approximately 2 than those from experiments, we found similar trends in experiments and simulations for these characteristic times as a function of composition. Namely, the collective and single-molecule orientational correlation times associated with Bz are observed to grow monotonically with the dilution of Bz, while those corresponding to Hf species exhibit a maximum at the equimolar composition. We attribute the quantitative discrepancy between experiments and simulations to the use of the Williams potential, which seems to overestimate the intermolecular interactions and thus predicts not only a slower translational dynamics but also a slower rotational diffusion dynamics than in real fluids.
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Affiliation(s)
- M Dolores Elola
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
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24
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Woods KN, Wiedemann H. The influence of chain dynamics on the far-infrared spectrum of liquid methanol-water mixtures. J Chem Phys 2005; 123:134507. [PMID: 16223314 DOI: 10.1063/1.2000239] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Far-infrared-absorption spectroscopy has been used to study the low-frequency (<or=100 cm-1) intermolecular modes of methanol in mixtures with water. With the aid of a first-principles molecular-dynamics simulation on an equivalent system, a detailed understanding about the origin of the low-frequency IR modes has been established. The total dipole spectrum from the simulation suggests that the bands appearing in the experimental spectra at approximately 55 and 70 cm-1 in methanol and methanol-rich mixtures arise from both fluctuations and torsional motions occurring within the methanol hydrogen-bonded chains. The influence of these modes on both the solvation dynamics and the relaxation mechanisms in the liquid is discussed within the context of recent experimental and theoretical results that have emerged from studies focusing on the short-time dynamics in the methanol hydrogen bond network.
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Affiliation(s)
- K N Woods
- BioPhysics Program, Stanford University, Stanford, California 94309, USA.
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Elola MD, Ladanyi BM. Polarizability response in polar solvents: Molecular-dynamics simulations of acetonitrile and chloroform. J Chem Phys 2005; 122:224506. [PMID: 15974690 DOI: 10.1063/1.1925275] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The relaxation of the many-body polarizability in liquid acetonitrile and chloroform at room temperature was studied by molecular-dynamics simulations. The collective polarizability induced by intermolecular interactions was included using first- and all-orders dipole-induced-dipole models and calculated considering both molecule-centered and distributed site polarizabilities. The anisotropic response was analyzed using a separation scheme that allows a decomposition of the total response in terms of orientational and collision-induced effects. We found the method effective in approximately separating the contributions of these relaxation mechanisms, although the orientational-collision-induced interference makes a non-negligible contribution to the total response. In both liquids the main contribution to the anisotropic response is due to orientational dynamics, but intermolecular collision-induced (or translational) effects are important, especially at short times. We found that higher-order interaction-induced effects were essentially negligible for both liquids. Larger differences were found between the center-center and site-site models, with the latter showing faster polarizability relaxation and better agreement with experiment. Isotropic and anisotropic spectra were computed from the corresponding time correlation functions. The lowest-frequency contributions are largely suppressed in the isotropic spectra and their overall shape is similar to the purely collision-induced contribution to the anisotropic spectra, but with an amplitude which is smaller by a factor of approximately 5 in acetonitrile and approximately 3 in chloroform.
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Affiliation(s)
- M Dolores Elola
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
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Sassi P, Paolantoni M, Cataliotti RS, Palombo F, Morresi A. Water/Alcohol Mixtures: A Spectroscopic Study of the Water-Saturated 1-Octanol Solution. J Phys Chem B 2004. [DOI: 10.1021/jp046647d] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paola Sassi
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy, and Istituto Nazionale di Fisica della Materia, Unità di Catania, 95100 Catania, Italy
| | - Marco Paolantoni
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy, and Istituto Nazionale di Fisica della Materia, Unità di Catania, 95100 Catania, Italy
| | - Rosario Sergio Cataliotti
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy, and Istituto Nazionale di Fisica della Materia, Unità di Catania, 95100 Catania, Italy
| | - Francesca Palombo
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy, and Istituto Nazionale di Fisica della Materia, Unità di Catania, 95100 Catania, Italy
| | - Assunta Morresi
- Dipartimento di Chimica, Sezione di Chimica Fisica, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy, and Istituto Nazionale di Fisica della Materia, Unità di Catania, 95100 Catania, Italy
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Ohkubo J, Kato T, Kono H, Fujimura Y. Molecular alignment in a liquid induced by a nonresonant laser field: Molecular dynamics simulation. J Chem Phys 2004; 120:9123-32. [PMID: 15267848 DOI: 10.1063/1.1704631] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We carried out molecular dynamics (MD) simulations for a dilute aqueous solution of pyrimidine in order to investigate the mechanisms of field-induced molecular alignment in a liquid phase. An anisotopically polarizable molecule can be aligned in a liquid phase by the interaction with a nonresonant intense laser field. We derived the effective forces induced by a nonresonant field on the basis of the concept of the average of the total potential over one optical cycle. The results of MD simulations show that a pyrimidine molecule is aligned in an aqueous solution by a linearly polarized field of light intensity I approximately 10(13) W/cm2 and wavelength lambda = 800 nm. The temporal behavior of field-induced alignment is adequately reproduced by the solution of the Fokker-Planck equation for a model system in which environmental fluctuations are represented by Gaussian white noise. From this analysis, we have revealed that the time required for alignment in a liquid phase is in the order of the reciprocals of rotational diffusion coefficients of a solute molecule. The degree of alignment is determined by the anisotropy of the polarizability of a molecule, light intensity, and temperature. We also discuss differences between the mechanisms of optical alignment in a gas phase and a liquid phase.
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Affiliation(s)
- Jun Ohkubo
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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Ryu S, Stratt RM. A Case Study in the Molecular Interpretation of Optical Kerr Effect Spectra: Instantaneous-Normal-Mode Analysis of the OKE Spectrum of Liquid Benzene. J Phys Chem B 2004. [DOI: 10.1021/jp0375665] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Seol Ryu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Richard M. Stratt
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
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Giraud G, Wynne K. A comparison of the low-frequency vibrational spectra of liquids obtained through infrared and Raman spectroscopies. J Chem Phys 2003. [DOI: 10.1063/1.1623747] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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