A Search for Two Types of Transverse Excitations in Liquid Polyvalent Metals at Ambient Pressure: An Ab Initio Molecular Dynamics Study of Collective Excitations in Liquid Al, Tl, and Ni

Bryk, Taras; Demchuk, Taras; Jakse, N.; Wax, J.-F.

doi:10.3389/fphy.2018.00006

Cited by 24 publications

(21 citation statements)

References 30 publications

(34 reference statements)

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“…The exploiting of the GBA in this framework can be relevant because features in the dynamic structure factor possibly related to the mixing of polarizations have been observed experimentally [50,54,109,110] and by MD simulations [55,56,58] in several liquids. Similar developments could also support the understanding of the origin of the two-peak structure observed in the transverse current spectra of liquids in the high-frequency region, as attested by recent MD studies [57,111,112].…”

Section: Discussionsupporting

confidence: 67%

Rayleigh scattering and disorder-induced mixing of polarizations in amorphous solids at the nanoscale: 1-octyl-3-methylimidazolium chloride glass

et al. 2020

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Acousticlike excitations in topologically disordered media at mesocale/nanoscale present anomalous features with respect to the Debye's theory. The so-called Rayleigh scattering manifests in a strong increase of the attenuation of the acousticlike excitations and a softening of the phase velocity with respect to its continuum limit value. Mean field models developed in the random media theory framework can successfully predict the occurrence, at the proper length scale, of Rayleigh scattering. The overall attenuation in the Rayleigh region is, however, underestimated. In the framework of random media theory we developed an analytical model, which permits a quantitative description of the acousticlike excitations in topological glasses in the whole first pseudo-Brillouin zone. The underestimation of the Rayleigh scattering is avoided and, importantly, the model allows to account also for the polarization properties of the acousticlike excitations. In a three-dimensional medium an acoustic wave is characterized by its phase velocity, intensity, and polarization. Rayleigh scattering emphasizes how the topological disorder affects the first two properties. The topological disorder is, however, expected to influence also the third one. In common with the Rayleigh scattering, hallmarks possibly related to the mixing of polarizations have been traced in different classes of amorphous solids at nanoscale. The quantitative theoretical approach developed permits to demonstrate how the mixing of polarizations generates a distinctive feature in the dynamic structure factor of amorphous solids. The modeling capability of the proposed mean field theory is tested on glassy 1-octyl-3-methylimidazolium chloride, whose spatial distribution of the elastic moduli is well assessed and can be experimentally characterized. Contrast between theoretical and experimental features for the selected glass reveals an excellent agreement. The mean field approach we present retains a certain degree of generality and can be possibly extended to different stochastic media or different wave fields.

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Section: Discussionsupporting

confidence: 67%

Rayleigh scattering and disorder-induced mixing of polarizations in amorphous solids at the nanoscale: 1-octyl-3-methylimidazolium chloride glass

et al. 2020

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“…Later on in ab initio molecular dynamics (AIMD) simulations of liquid Li [19] revealed that at high pressures the transverse current spectral functions showed a two-peak structure, which became more pronounced with increasing pressure. Later on similar findings were observed even at ambient pressure in liquid Tl [20].…”

Section: Introductionsupporting

confidence: 73%

Structural and dynamic features of liquid Si under high pressure above the melting line minimum

Demchuk,

Bryk,

Seitsonen

2020

Preprint

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We report an ab initio simulation study of changes in structural and dynamic properties of liquid Si at 7 pressures ranging from 10.2 GPa to 24.3 GPa along the isothermal line 1150 K, which is above the minimum of the melting line. The increase of pressure from 10.2 GPa to 16 GPa causes strong reduction in the tetrahedral ordering of the most close neighbors. The diffusion coefficient shows a linear decay vs drop in atomic volume, that agrees with theoretical prediction for simple liquid metals, thus not showing any feature at the pressures corresponding to the different crystal phase boundaries. The Fourier-spectra of velocity autocorrelation function shows two-peak structure at pressures 20 GPa and higher. These characteristic frequencies correspond well to the peak frequencies of the transverse current spectral function in the second pseudo-Brillouin zone.Two almost flat branches of short-wavelength transverse modes were observed for all the studied pressures. We discuss the pressure evolution of characteristic frequencies in the longitudinal and transverse branches of collective modes.

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“…The appearance of another, high frequency branch in the transvese dispersion relation, had been reported first in some liquid metals at high pressure, i.e., Li, Na, Fe, Al and Pb, [2,[64][65][66]. Subsequently, it was also found in l-Tl and l-Pb [64,66,67] at ambient pressure.…”

Section: Collective Dynamicsmentioning

confidence: 87%

First principles determination of some static and dynamic properties of the liquid 3d transition metals near melting

Río¹,

Pascual²,

Rodríguez³

et al. 2020

Condens. Matter Phys.

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We report an ab initio molecular dynamics simulation study of several static and dynamic properties of the liquid 3d transition metals. The calculated static structure factors show qualitative agreement with the available experimental data, and its second peak displays an asymmetric shape which suggests a significant local icosahedral short-range order. The dynamical structure reveals propagating density fluctuations whose dispersion relation has been evaluated; moreover, its long wavelength limit is compatible with their respective experimental sound velocity. Results are reported for the longitudinal and transverse current spectral functions as well as for the respective dispersion relations. We also analyze the possible appearance of transverse-like low-energy excitations in the calculated dynamic structure factors. Several transport coefficients have been evaluated and compared with the available experimental data.

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A Search for Two Types of Transverse Excitations in Liquid Polyvalent Metals at Ambient Pressure: An Ab Initio Molecular Dynamics Study of Collective Excitations in Liquid Al, Tl, and Ni

Cited by 24 publications

References 30 publications

Rayleigh scattering and disorder-induced mixing of polarizations in amorphous solids at the nanoscale: 1-octyl-3-methylimidazolium chloride glass

Rayleigh scattering and disorder-induced mixing of polarizations in amorphous solids at the nanoscale: 1-octyl-3-methylimidazolium chloride glass

Structural and dynamic features of liquid Si under high pressure above the melting line minimum

First principles determination of some static and dynamic properties of the liquid 3d transition metals near melting

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