Concentration fluctuations and boson peak in a binary metallic glass: A generalized collective modes study

Bryk, Taras; Mryglod, I. M.

doi:10.1103/physrevb.82.174205

Cited by 15 publications

(10 citation statements)

References 48 publications

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“…3 and compared to the long wavelength, hydrodynamic limit, derived according to the generalized Langevin equation adapted to the glassy state, i.e. taking into account the non-ergodicity factor f(Q) (estimated via Eq.3)383940. Accordingly, for an harmonic glassy system, the Q-dependency of v a ( Q ) reads: normalised in Fig.…”

Section: Discussionmentioning

confidence: 99%

Acoustic-like dynamics of amorphous drugs in the THz regime

Pogna

Rodríguez-Tinoco

Krisch

et al. 2013

Sci Rep

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The high frequency dynamics of Indomethacin and Celecoxib glasses has been investigated by inelastic x-ray scattering, accessing a momentum-energy region still unexplored in amorphous pharmaceuticals. We find evidence of phonon-like acoustic dynamics, and determine the THz behavior of sound velocity and acoustic attenuation. Connections with ordinary sound propagation are discussed, along with the relation between fast and slow degrees of freedom as represented by non-ergodicity factor and kinetic fragility, respectively.

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Section: Discussionmentioning

confidence: 99%

Acoustic-like dynamics of amorphous drugs in the THz regime

Pogna

Rodríguez-Tinoco

Krisch

et al. 2013

Sci Rep

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“…66 In the case of the N vvariable dynamic model for glass systems, the GCM replica has the following expression…”

Section: Extended Viscoelastic Model For Transverse Dynamicsmentioning

confidence: 99%

Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures

Bryk

Ruocco

Scopigno

et al. 2015

The Journal of Chemical Physics

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Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations in liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the transverse current spectral functions, density of vibrational states, and dispersions of collective excitations yield evidence of two types of propagating modes that contribute strongly to transverse dynamics. Emergence of the unusually high-frequency transverse modes gives evidence of the breakdown of a regular viscoelastic theory of transverse dynamics, which is based on coupling of a single transverse propagating mode with shear relaxation. The explanation of the observed high-frequency shift above the viscoelastic value is given by the presence of another branch of collective excitations. With the pressure increasing, coupling between the two types of collective excitations is rationalized within a proposed extended viscoelastic model of transverse dynamics. Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations in liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the...

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“…At present, the nature of quasilocal vibrational modes is being discussed to clarify their role in heat transport under the conditions of heavy resonance scattering of sound modes when acoustic and quasilocal low-frequency vibrational modes are actually interdependent excitations. The hybridization of phonons and local vibrational modes in the Ioffe-Regel crossover for inelastic scattering determines both the behavior of thermal conductivity and the other thermal and dynamic properties of glasses [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Deuteration effects in the thermal conductivity of molecular glasses

Кривчиков

Bermejo

Sharapova

et al. 2011

Low Temperature Physics

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The thermal conductivity κ(T) of pure deuterated ethanol has been measured under its equilibrium vapor pressure in its orientationally-ordered crystal (T = 2 K -T m ), orientational glass and the glass state (T = 2 K -T g , T g is the glass transition temperature) solid phases. The temperature dependence of the conductivity is well described by a sum of two contributions: κ(T) = κ I (T) + κ II (T), where κ I (T) account for the heat transport by acoustic phonons and κ II (T) for the heat transfer by localized high-frequency excitations respectively. The thermal conductivities of deuterated and hydrogenated ethanols are compared in different phases. The phonon scattering mechanisms in the glasses have been analyzed. In the investigated glasses the effect of complete deuteration shows up as a contribution κ II (T).

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Concentration fluctuations and boson peak in a binary metallic glass: A generalized collective modes study

Cited by 15 publications

References 48 publications

Acoustic-like dynamics of amorphous drugs in the THz regime

Acoustic-like dynamics of amorphous drugs in the THz regime

Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures

Deuteration effects in the thermal conductivity of molecular glasses

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