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Shen Z, Carrillo JMY, Sumpter BG, Wang Y. Mesoscopic two-point collective dynamics of glass-forming liquids. J Chem Phys 2023; 159:114501. [PMID: 37712790 DOI: 10.1063/5.0161866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/24/2023] [Indexed: 09/16/2023] Open
Abstract
The collective density-density and hydrostatic pressure-pressure correlations of glass-forming liquids are spatiotemporally mapped out using molecular dynamics simulations. It is shown that the sharp rise of structural relaxation time below the Arrhenius temperature coincides with the emergence of slow, nonhydrodynamic collective dynamics on mesoscopic scales. The observed long-range, nonhydrodynamic mode is independent of wave numbers and closely coupled to the local structural dynamics. Below the Arrhenius temperature, it dominates the slow collective dynamics on length scales immediately beyond the first structural peak in contrast to the well-known behavior at high temperatures. These results highlight a key connection between the qualitative change in mesoscopic two-point collective dynamics and the dynamic crossover phenomenon.
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Affiliation(s)
- Zhiqiang Shen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Jan-Michael Y Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yangyang Wang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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2
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Alvarez F, Arbe A, Colmenero J. Unraveling the coherent dynamic structure factor of liquid water at the mesoscale by molecular dynamics simulations. J Chem Phys 2021; 155:244509. [PMID: 34972354 DOI: 10.1063/5.0074588] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present an investigation by molecular dynamics (MD)-simulations of the coherent dynamic structure factor, S(Q, t) (Q: momentum transfer), of liquid water at the mesoscale (0.1 Å-1 ≤ Q ≤ Qmax) [Qmax ≈ 2 Å-1: Q-value of the first maximum of the static structure factor, S(Q), of water]. The simulation cell-large enough to address the collective properties at the mesoscale-is validated by direct comparison with recent results on the dynamic structure factor in the frequency domain obtained by neutron spectroscopy with polarization analysis [Arbe et al., Phys. Rev. Res. 2, 022015 (2020)]. We have not only focused on the acoustic excitations but also on the relaxational contributions to S(Q, t). The analysis of the MD-simulation results-including the self- and distinct contributions to the diffusive part of S(Q, t)-nicely explains why the relaxation process hardly depends on Q in the low Q-range (Q ≤ 0.4 Å-1) and how it crosses over to a diffusion-driven process at Q ≈ Qmax. Our simulations also give support to the main assumptions of the model used to fit the experimental data in the above mentioned paper. The application of such a model to the simulation S(Q, t) data delivers (i) results for the relaxation component of S(Q, t) in agreement with those obtained from neutron experiments and (ii) longitudinal and transverse hydrodynamic-like components with similar features than those identified in previous simulations of the longitudinal and transverse current spectra directly. On the other hand, in general, our MD-simulations results of S(Q, t) qualitatively agree with the viscoelastic transition framework habitually used to describe inelastic x-ray scattering results.
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Affiliation(s)
- Fernando Alvarez
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - Arantxa Arbe
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - Juan Colmenero
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
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Szabó S, Yang F, Lohstroh W, Petry W. Self-diffusion in single component liquid metals: a case study of mercury. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:375101. [PMID: 34241596 DOI: 10.1088/1361-648x/ac0d83] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
We report the temperature dependent atomic dynamics in mercury investigated with quasi-elastic neutron scattering between 240 and 350 K. The self-diffusivity follows an Arrhenius behavior over the entire investigated temperature range, with an activation energy of 41.8 ± 1.4 meV. The standard deviation is in the order of 5%, significantly more precise than previously reported measurements in the literature. Similar to alkali metal melts, the self-diffusion coefficient close to the melting point can be predicted with an effective atom radius of 1.37 Å. This shows a dominant contribution from the repulsive part of the interatomic potential to the mass transport. We observed deviations from the Stokes/Sutherland-Einstein relation and indications of an increasing collective nature of the dynamics with decreasing temperature. Thus, a transport mechanism of uncorrelated binary collisions cannot fully describe the temperature dependence of the self-diffusion.
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Affiliation(s)
- Sandro Szabó
- Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department, Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Fan Yang
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Wiebke Lohstroh
- Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department, Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Winfried Petry
- Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department, Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
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4
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Petrillo C, Sacchetti F. Future applications of the high-flux thermal neutron spectroscopy: the ever-green case of collective excitations in liquid metals. ADVANCES IN PHYSICS: X 2021. [DOI: 10.1080/23746149.2021.1871862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Affiliation(s)
- Caterina Petrillo
- Department of Physics & Earth Science, University of Perugia, Perugia, Italy
| | - Francesco Sacchetti
- Department of Physics & Earth Science, University of Perugia, Perugia, Italy
- National Research Council, Institute IOM-CNR, Perugia, Italy
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5
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Fasolato C, Sacchetti F, Postorino P, Tozzi P, Principi E, Simoncig A, Foglia L, Mincigrucci R, Bencivenga F, Masciovecchio C, Petrillo C. Ultrafast Plasmon Dynamics in Crystalline LiF Triggered by Intense Extreme UV Pulses. PHYSICAL REVIEW LETTERS 2020; 124:184801. [PMID: 32441964 DOI: 10.1103/physrevlett.124.184801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 02/12/2020] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
An extreme ultraviolet pump and visible-light probe transmission experiment in crystalline LiF, carried out at the Free Electron Laser facility FERMI, revealed an oscillating time dependence of the plasmon mode excited in the high-density high-temperature electron plasma. The effect is interpreted as a fingerprint of the electron-ion interaction: the ion motion, shaped by the electron dynamic screening, induces, in turn, electron density fluctuations that cause the oscillation of the plasmon frequency at the timescale of the ion dynamics. Fitting the high resolution transmission data with an RPA model for the temperature-dependent dielectric function, which includes electron self-energy and electron-ion coupling, confirms the interpretation of the time modulation of the plasmon mode.
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Affiliation(s)
- C Fasolato
- Università di Perugia, Dipartimento di Fisica e Geologia, I-06123 Perugia, Italy
| | - F Sacchetti
- Università di Perugia, Dipartimento di Fisica e Geologia, I-06123 Perugia, Italy
- CNR Istituto Officina dei Materiali (IOM), I-06123 Perugia, Italy
| | - P Postorino
- CNR Istituto Officina dei Materiali (IOM), I-06123 Perugia, Italy
- Università di Roma Sapienza, Dipartimento di Fisica, I-00100 Roma, Italy
| | - P Tozzi
- CNR Istituto Officina dei Materiali (IOM), I-06123 Perugia, Italy
| | - E Principi
- Elettra-Sincrotrone Trieste SCpA, I-34149 Basovizza, Trieste, Italy
| | - A Simoncig
- Elettra-Sincrotrone Trieste SCpA, I-34149 Basovizza, Trieste, Italy
| | - L Foglia
- Elettra-Sincrotrone Trieste SCpA, I-34149 Basovizza, Trieste, Italy
| | - R Mincigrucci
- Elettra-Sincrotrone Trieste SCpA, I-34149 Basovizza, Trieste, Italy
| | - F Bencivenga
- Elettra-Sincrotrone Trieste SCpA, I-34149 Basovizza, Trieste, Italy
| | - C Masciovecchio
- Elettra-Sincrotrone Trieste SCpA, I-34149 Basovizza, Trieste, Italy
| | - C Petrillo
- Università di Perugia, Dipartimento di Fisica e Geologia, I-06123 Perugia, Italy
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6
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Demmel F, Szubrin D, Pilgrim WC, De Francesco A, Formisano F. Transition from hydrodynamic to viscoelastic propagation of sound in molten RbBr. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:012307. [PMID: 26274162 DOI: 10.1103/physreve.92.012307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Indexed: 06/04/2023]
Abstract
Inelastic neutron scattering was applied to measure the acoustic-type excitations in the molten alkali halide rubidium bromide. For molten RbBr neutron scattering is mainly sensitive to the number density fluctuation spectrum and is not influenced by charge fluctuations. Utilizing a dedicated Brillouin scattering spectrometer, we focused on the small-wave-vector range. From inelastic excitations in the spectra a dispersion relation was obtained, which shows a large positive dispersion effect. This frequency enhancement is related to a viscoelastic response of the liquid at high frequencies. Towards small wave vectors we identify the transition to hydrodynamic behavior. This observation is supported by a transition of the sound velocity from a viscoelastic enhanced value to the adiabatic speed of sound for the acoustic-type excitations. Furthermore, the spectrum transforms into a line shape compatible with a prediction from hydrodynamics.
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Affiliation(s)
- F Demmel
- ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - D Szubrin
- Fachbereich Chemie, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - W C Pilgrim
- Fachbereich Chemie, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - A De Francesco
- CNR-IOM c/o OGG Institut Laue-Langevin, 38042 Grenoble, France
| | - F Formisano
- CNR-IOM c/o OGG Institut Laue-Langevin, 38042 Grenoble, France
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7
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Zanatta M, Sacchetti F, Guarini E, Orecchini A, Paciaroni A, Sani L, Petrillo C. Collective ion dynamics in liquid zinc: evidence for complex dynamics in a non-free-electron liquid metal. PHYSICAL REVIEW LETTERS 2015; 114:187801. [PMID: 26001017 DOI: 10.1103/physrevlett.114.187801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Indexed: 06/04/2023]
Abstract
A detailed inelastic neutron scattering investigation of the THz dynamics of liquid zinc is presented. The observed Q dependence clearly reveals the existence of a complex dynamics made up of two distinct excitations. The highest energy mode is the prolongation of the longitudinal acoustic density fluctuations whereas the comparison with the phonon dynamics of crystalline hcp zinc suggests a transverse acousticlike nature for the second one. This mode seems related to peculiar anisotropic interactions, possibly connected to the behavior of the crystalline phase.
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Affiliation(s)
- M Zanatta
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
- Istituto Officina Materiali, Unità di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
| | - F Sacchetti
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
- Istituto Officina Materiali, Unità di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
| | - E Guarini
- Dipartimento di Fisica e Astronomia, Università di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - A Orecchini
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
| | - A Paciaroni
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
| | - L Sani
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
| | - C Petrillo
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
- Istituto Officina Materiali, Unità di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy
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8
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Ayrinhac S, Gauthier M, Bove LE, Morand M, Le Marchand G, Bergame F, Philippe J, Decremps F. Equation of state of liquid mercury to 520 K and 7 GPa from acoustic velocity measurements. J Chem Phys 2014; 140:244201. [DOI: 10.1063/1.4882695] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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9
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Calderín L, González LE, González DJ. Static, dynamic and electronic properties of expanded fluid mercury in the metal-nonmetal transition range. An ab initio study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:375105. [PMID: 21878714 DOI: 10.1088/0953-8984/23/37/375105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fluid Hg undergoes a metal-nonmetal (M-NM) transition when expanded toward a density of around 9 g cm(-3). We have performed ab initio molecular dynamics simulations for several thermodynamic states around the M-NM transition range and the associated static, dynamic and electronic properties have been analyzed. The calculated static structure shows a good agreement with the available experimental data. It is found that the volume expansion decreases the number of nearest neighbors from 10 (near the triple point) to around 8 at the M-NM transition region. Moreover, these neighbors are arranged into two subshells and the decrease in the number of neighbors occurs in the inner subshell. The calculated dynamic structure factors agree fairly well with their experimental counterparts obtained by inelastic x-ray scattering experiments, which display inelastic side peaks. The derived dispersion relation exhibits some positive dispersion for all the states, although its value around the M-NM transition region is not as marked as suggested by the experiment. We have also calculated the electronic density of states, which shows the appearance of a gap at a density of around 8.3 g cm(-3).
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Affiliation(s)
- L Calderín
- Research Computing and Cyberinfrastructure, The Pennsylvania State University, University Park, PA 16802, USA
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10
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Abstract
Abstract
X-ray diffraction, small angle X-ray scattering and preliminary inelastic X-ray scattering measurements for a metallic fluid up to the supercritical region have been carried out using synchrotron radiation at SPring-8. We obtained the structure factor, S(k), and the pair distribution functions, g(r), for expanded fluid Hg from the liquid to the dense vapour region by X-ray diffraction measurements. Change of the local structure in the metalinsulator transition in fluid Hg is discussed. To obtain information on the density fluctuation in fluid Hg near the critical point, small angle X-ray scattering measurements were carried out at SPring-8. In addition to the static structures, the dynamic structure factor of expanded fluid Hg was obtained for the first time using inelastic X-ray scattering technique newly established at a synchrotron radiation facility of the third generation source. Preliminary results of the first experiment are presented.
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11
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Calderín L, González LE, González DJ. Ab initio molecular dynamics study of the static, dynamic, and electronic properties of liquid mercury at room temperature. J Chem Phys 2009; 130:194505. [DOI: 10.1063/1.3137582] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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12
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González LE, González DJ, Calderín L, Şengül S. On the behavior of single-particle dynamic properties of liquid Hg and other metals. J Chem Phys 2008; 129:171103. [DOI: 10.1063/1.3020717] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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13
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Bove LE, Petrillo C, Fontana A, Sokolov AP. Damping of sound waves in the terahertz range and strength of the boson peak. J Chem Phys 2008; 128:184502. [DOI: 10.1063/1.2912060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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Guarini E, Sampoli M, Venturi G, Bafile U, Barocchi F. Inelastic neutron scattering and molecular dynamics determination of the interaction potential in liquid CD4. PHYSICAL REVIEW LETTERS 2007; 99:167801. [PMID: 17995296 DOI: 10.1103/physrevlett.99.167801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Indexed: 05/25/2023]
Abstract
Anisotropic interactions of liquid CD4 are studied in detail by comparison of inelastic neutron Brillouin scattering data with molecular dynamics simulations using up to four different models of the methane site-site potential. We demonstrate that the experimental dynamic structure factor S(Q,omega) acts as a highly discriminating quantity for possible interaction schemes. In particular, the Q evolution of the spectra enables a selective probing of the short- and medium-range features of the anisotropic potentials. We show that the preferential configuration of methane dimers at liquid densities can thus be discerned by analyzing the orientation-dependent model potential curves, in light of the experimental and simulation results.
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Affiliation(s)
- E Guarini
- Dipartimento di Fisica, Università di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
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15
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Bafile U, Guarini E, Barocchi F. Collective acoustic modes as renormalized damped oscillators: unified description of neutron and x-ray scattering data from classical fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:061203. [PMID: 16906814 DOI: 10.1103/physreve.73.061203] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Indexed: 05/11/2023]
Abstract
In the Q range where inelastic x-ray and neutron scattering are applied to the study of acoustic collective excitations in fluids, various models of the dynamic structure factor S(Q, omega) generalize in different ways the results obtained from linearized-hydrodynamics theory in the Q-->0 limit. Here we show that the models most commonly fitted to experimental S(Q, omega) spectra can be given a unified formulation. In this way, direct comparisons among the results obtained by fitting different models become now possible to a much larger extent than ever. We also show that a consistent determination of the dispersion curve and of the propagation Q range of the excitations is possible, whichever model is used. We derive an exact formula which describes in all cases the dispersion curve and allows for the first quantitative understanding of its shape, by assigning specific and distinct roles to the various structural, thermal, and damping effects that determine the Q dependence of the mode frequencies. The emerging picture describes the acoustic modes as Q-dependent harmonic oscillators whose characteristic frequency is explicitly renormalized in an exact way by the relaxation processes, which also determine, through the widths of both the inelastic and the elastic lines, the whole shape of collective-excitation spectra.
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Affiliation(s)
- Ubaldo Bafile
- Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano, I-50019 Sesto Fiorentino, Italy
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16
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Patty M, Schoen K, Montfrooij W. Fluctuating magnetic moments in liquid metals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:021202. [PMID: 16605328 DOI: 10.1103/physreve.73.021202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Indexed: 05/08/2023]
Abstract
We reanalyze literature data on neutron scattering by liquid metals and show that there is an additional broad (in energy) quasielastic mode present that is absent in x-ray scattering. This mode cannot be accounted for by the standard coherent and incoherent scattering mechanisms. We argue that this mode indicates that nonmagnetic liquid metals possess a magnetic moment which fluctuates on a picosecond time scale. This time scale is the same as the time scale of the cage-diffusion process in which an ion rattles around in the cage formed by its neighbors. We find that these fluctuating magnetic moments are present in liquid Hg, Al, Ga, and Pb and possibly also in the alkali metals.
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Affiliation(s)
- Mark Patty
- Department of Physics and Astronomy, and Missouri Research Reactor, University of Missouri, Columbia, Missouri 65211, USA
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17
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Ishikawa D, Inui M, Matsuda K, Tamura K, Tsutsui S, Baron AQR. Fast sound in expanded fluid Hg accompanying the metal-nonmetal transition. PHYSICAL REVIEW LETTERS 2004; 93:097801. [PMID: 15447141 DOI: 10.1103/physrevlett.93.097801] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2004] [Indexed: 05/24/2023]
Abstract
The dynamic structure factor S(Q,omega) of expanded fluid Hg has been measured up to the metal-nonmetal transition region at 9.0 g cm(-3) (1723 K and 1940 bars) using high-resolution inelastic x-ray scattering, at momentum transfers, Q, from 0.2 to 4.8 A(-1). Analysis in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The effective sound velocity at 9.0 g cm(-3) estimated from the dispersion relation is triple the ultrasonic sound velocity. The present result suggests the existence of fast sound in expanded fluid Hg accompanying the metal-nonmetal transition.
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Affiliation(s)
- D Ishikawa
- Graduate School of Engineering, Kyoto University, Kyoto, 606-8501, Japan
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18
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Jahn S, Suck JB. Atomic dynamics in liquids with competing interactions. PHYSICAL REVIEW LETTERS 2004; 92:185507. [PMID: 15169502 DOI: 10.1103/physrevlett.92.185507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Indexed: 05/24/2023]
Abstract
The influence of the type of atomic interaction on the atomic dynamics is studied for liquid Na(x)Sn(1-x) (x = 0.9, 0.77, 0.57, 0.5, 0.33) alloys by cold neutron inelastic scattering. The dispersions obtained from the longitudinal current correlation function J(l)(Q,omega) show clear evidence for the dependence of the dynamics on the type of interaction (metallic, ionic, partly covalent) tuned by changing the composition of the alloy. For the first time, a second dispersion branch is observed in the total J(l)(Q,omega) around Q(p), the position of the principal peak of S(Q), for the Sn-rich compositions. The dynamic properties are discussed and compared to results of recent ab initio molecular dynamics simulations.
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Affiliation(s)
- Sandro Jahn
- Institute of Physics, Materials Research and Liquids, TU Chemnitz, 09107 Chemnitz, Germany.
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19
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Badyal YS, Bafile U, Miyazaki K, de Schepper IM, Montfrooij W. Cage diffusion in liquid mercury. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:061208. [PMID: 14754193 DOI: 10.1103/physreve.68.061208] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2003] [Indexed: 05/24/2023]
Abstract
We present inelastic neutron scattering measurements on liquid mercury at room temperature for wave numbers q in the range 0.3 <q<7.0 A(-1). We find that the energy half width of the incoherent part of the dynamic structure factor S(q,E) is determined by a self-diffusion process. The half width of the coherent part of S(q,E) shows the characteristic behavior expected for a cage diffusion process. We also show that the response function at small wave numbers exhibits a quasielastic mode with a time scale characteristic of cage diffusion, however, its intensity is larger by an order of magnitude than what would be expected for cage diffusion. We speculate on a scenario in which the intensity of the cage diffusion mode at small wave numbers is amplified through a valence fluctuation mechanism.
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Affiliation(s)
- Yaspal S Badyal
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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20
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Tóth G. An iterative scheme to derive pair potentials from structure factors and its application to liquid mercury. J Chem Phys 2003. [DOI: 10.1063/1.1543142] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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21
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Scopigno T, Filipponi A, Krisch M, Monaco G, Ruocco G, Sette F. High-frequency acoustic modes in liquid gallium at the melting point. PHYSICAL REVIEW LETTERS 2002; 89:255506. [PMID: 12484899 DOI: 10.1103/physrevlett.89.255506] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2002] [Indexed: 05/24/2023]
Abstract
The microscopic dynamics in liquid gallium at melting has been studied by inelastic x-ray scattering. We demonstrate the existence of acousticlike modes up to wave vectors above one-half of the first maximum of the static structure factor, at variance with earlier results from inelastic neutron scattering [F. J. Bermejo et al., Phys. Rev. E 49, 3133 (1994)]. Despite structural (extremely rich polymorphism) and electronic (mixed valence) peculiarities, the collective dynamics is strikingly similar to the one of van der Waals and metallic fluids. This result speaks in favor of the universality of the short time dynamics in monatomic liquids rather than of system-specific dynamics.
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Affiliation(s)
- T Scopigno
- Dipartimento di Fisica and INFM, Universitá di Roma La Sapienza, Italy
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