The theory of elasticity with spatially fluctuating elastic constants (heterogeneous-elasticity theory) is reviewed. It is shown that the vibrational anomalies associated with the boson peak can be qualitatively and quantitatively explained in terms of this theory. Two versions of a mean-field theory for solving the stochastic equation of motion are presented: the coherent-potential approximation (CPA) and the self-consistent Born approximation (SCBA). It is shown that the latter is included in the former in the Gaussian and weak-disorder limit. We are able to discuss and explain cases in which the change of the vibrational spectrum by varying an external parameter can be accounted for by changing the Debye frequency (elastic transformation) and cases in which this is not possible. In the latter case a change in the distribution of the elastic moduli has occurred

Theory of vibrational anomalies in glasses / Schirmacher, Walter; Scopigno, Tullio; Ruocco, Giancarlo. - In: JOURNAL OF NON-CRYSTALLINE SOLIDS. - ISSN 0022-3093. - STAMPA. - 407:(2015), pp. 133-140. [10.1016/j.jnoncrysol.2014.09.054]

Theory of vibrational anomalies in glasses

SCHIRMACHER, WALTER;SCOPIGNO, TULLIO;RUOCCO, Giancarlo
2015

Abstract

The theory of elasticity with spatially fluctuating elastic constants (heterogeneous-elasticity theory) is reviewed. It is shown that the vibrational anomalies associated with the boson peak can be qualitatively and quantitatively explained in terms of this theory. Two versions of a mean-field theory for solving the stochastic equation of motion are presented: the coherent-potential approximation (CPA) and the self-consistent Born approximation (SCBA). It is shown that the latter is included in the former in the Gaussian and weak-disorder limit. We are able to discuss and explain cases in which the change of the vibrational spectrum by varying an external parameter can be accounted for by changing the Debye frequency (elastic transformation) and cases in which this is not possible. In the latter case a change in the distribution of the elastic moduli has occurred
2015
Condensed Matter Physics; ceramics and composites; electronic, optical and magnetic materials; Materials Chemistry; metals and alloys
01 Pubblicazione su rivista::01a Articolo in rivista
Theory of vibrational anomalies in glasses / Schirmacher, Walter; Scopigno, Tullio; Ruocco, Giancarlo. - In: JOURNAL OF NON-CRYSTALLINE SOLIDS. - ISSN 0022-3093. - STAMPA. - 407:(2015), pp. 133-140. [10.1016/j.jnoncrysol.2014.09.054]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/838558
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