Collective Ion Dynamics in Liquid Zinc: Evidence for Complex Dynamics in a Non-Free-Electron Liquid Metal

Zanatta, M.; Sacchetti, F.; Guarini, Eleonora; Orecchini, A.; Paciaroni, Alessandro; Sani, Lorenzo; Petrillo, C.

doi:10.1103/physrevlett.114.187801

Cited by 46 publications

(48 citation statements)

References 31 publications

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“…Similar findings were reported from a fit analysis of IXS experiments for liquid Na at temperature 393 K, 14 Cu at 1423 K, 15 Fe at 1823 K, 15 and Zn at 713 K, 15 and another result from INS experiments on liquid Zn at 773 K was reported in Ref. 16.…”

Section: Introductionsupporting

confidence: 89%

A search for manifestation of two types of collective excitations in dynamic structure of a liquid metal: Ab initio study of collective excitations in liquid Na

Bryk

Wax

2016

The Journal of Chemical Physics

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Using a combination of ab initio molecular dynamics and several fit models for dynamic structure of liquid metals, we explore an issue of possible manifestation of non-acoustic collective excitations in longitudinal dynamics having liquid Na as a case study. A model with two damped harmonic oscillators (DHOs) in time domain is used for analysis of the density-density time correlation functions. Another similar model with two propagating contributions and three lowest exact sum rules is considered, as well as an extended hydrodynamic model known as thermo-viscoelastic one which permits two types of propagating modes outside the hydrodynamic region to be used for comparison with ab initio obtained time correlation functions and calculations of dispersions of collective excitations. Our results do not support recent suggestions that, even in simple liquid metals, non-hydrodynamics transverse excitations contribute to the longitudinal collective dynamics and can be detected as a DHO-like spectral shape at their transverse frequency. We found that the thermo-viscoelastic dynamic model permits perfect description of the density-density and current-current time correlation functions of the liquid Na in a wide range of wave numbers, which implies that the origin of the non-hydrodynamic collective excitations contributing to longitudinal dynamics can be short-wavelength heat waves.

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Section: Introductionsupporting

confidence: 89%

A search for manifestation of two types of collective excitations in dynamic structure of a liquid metal: Ab initio study of collective excitations in liquid Na

Bryk

Wax

2016

The Journal of Chemical Physics

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“…Nevertheless, some doubt that HB may be the responsible for shear waves descends from the literature of the last decade, as commented on in a very recent paper 17 . In fact, that work and several papers therein quoted 18 – 23 have shown that propagating shear modes are not a peculiarity of HB liquids. However, while in some liquid metals 18 – 23 transverse modes have been detected directly in the dynamic structure factor S ( Q , ω ), this was not the case of liquid gold 24 , where their presence has been assessed 17 only through the analysis of the density of states (DoS) of the liquid, i.e.…”

Section: Introductionmentioning

confidence: 90%

Switching off hydrogen-bond-driven excitation modes in liquid methanol

Bellissima

González

Bafile

et al. 2017

Sci Rep

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Hydrogen bonding plays an essential role on intermolecular forces, and consequently on the thermodynamics of materials defined by this elusive bonding character. It determines the property of a vital liquid as water as well as many processes crucial for life. The longstanding controversy on the nature of the hydrogen bond (HB) can be settled by looking at the effect of a vanishing HB interaction on the microscopic properties of a given hydrogen-bonded fluid. This task suits the capabilities of computer simulations techniques, which allow to easily switch off HB interactions. We then use molecular dynamics to study the microscopic properties of methanol, a prototypical HB liquid. Fundamental aspects of the dynamics of methanol at room temperature were contextualised only very recently and its rich dynamics was found to have striking analogies with that of water. The lower temperature (200 K) considered in the present study led us to observe that the molecular centre-of-mass dynamics is dominated by four modes. Most importantly, the computational ability to switch on and off hydrogen bonds permitted us to identify which, among these modes, have a pure HB-origin. This clarifies the role of hydrogen bonds in liquid dynamics, disclosing new research opportunities and unexplored interpretation schemes.

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“…It has to be noted that the relationship between collective dynamics and density of states is a general property, not restricted to the longitudinal wave case only. For example, in a recent work [41], the density of states of the crystal phase has been used to interpret dynamic structure factor data of a liquid metal, where an excitation was observed at frequencies close to those of the transverse phonon density of states and was therefore assigned a transverselike character.…”

Section: B Sound Modesmentioning

confidence: 99%

Density of states and dynamical crossover in a dense fluid revealed by exponential mode analysis of the velocity autocorrelation function

et al. 2017

Self Cite

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Extending a preceding study of the velocity autocorrelation function (VAF) in a simulated Lennard-Jones fluid [Phys. Rev. E 92, 042166 (2015)] to cover higher-density and lower-temperature states, we show that the recently demonstrated multi-exponential expansion method allows for a full account and understanding of the basic dynamical processes encompassed by a fundamental quantity as the VAF. In particular, besides obtaining evidence of a persisting long-time tail, we assign specific and unambiguous physical meanings to groups of exponential modes related to the longitudinal and transverse collective dynamics, respectively. We have made this possible by consistently introducing the interpretation of the VAF frequency spectrum as a global density of states in fluids, generalizing a solid-state concept, and by giving to specific spectral components, obtained through the VAF exponential expansion, the corresponding meaning of partial densities of states relative to specific dynamical processes. The clear identification of a high-frequency oscillation of the VAF with the near-top excitation frequency in the dispersion curve of acoustic waves is a neat example of the power of the method. As for the transverse mode contribution, its analysis turns out to be particularly important, because the multi-exponential expansion reveals a transition marking the onset of propagating excitations when the density is increased beyond a threshold value. While this finding agrees with the recent literature debating the issue of dynamical crossover boundaries, such as the one identified with the Frenkel line, we can add detailed information on the modes involved in this specific process in the domains of both time and frequency. This will help obtain a still missing full account of transverse dynamics, in both its nonpropagating and propagating aspects which are linked through dynamical transitions depending on both the thermodynamic states and the excitation wavevectors.

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Collective Ion Dynamics in Liquid Zinc: Evidence for Complex Dynamics in a Non-Free-Electron Liquid Metal

Cited by 46 publications

References 31 publications

A search for manifestation of two types of collective excitations in dynamic structure of a liquid metal: Ab initio study of collective excitations in liquid Na

A search for manifestation of two types of collective excitations in dynamic structure of a liquid metal: Ab initio study of collective excitations in liquid Na

Switching off hydrogen-bond-driven excitation modes in liquid methanol

Density of states and dynamical crossover in a dense fluid revealed by exponential mode analysis of the velocity autocorrelation function

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