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dc.contributor.authorMarruzzo, Alessia
dc.contributor.authorKöhler, Stephan
dc.contributor.authorFratalocchi, Andrea
dc.contributor.authorRuocco, Giancarlo
dc.contributor.authorSchirmacher, Walter
dc.date.accessioned2015-08-03T10:43:41Z
dc.date.available2015-08-03T10:43:41Z
dc.date.issued2013-01-31
dc.identifier.citationMarruzzo, A., Köhler, S., Fratalocchi, A., Ruocco, G., & Schirmacher, W. (2013). Vibrational anomalies and marginal stability of glasses. The European Physical Journal Special Topics, 216(1), 83–93. doi:10.1140/epjst/e2013-01731-5
dc.identifier.issn19516355
dc.identifier.doi10.1140/epjst/e2013-01731-5
dc.identifier.urihttp://hdl.handle.net/10754/562583
dc.description.abstractThe experimentally measured vibrational spectrum of glasses strongly deviates from that expected in Debye's elasticity theory: The density of states deviates from Debye's ω2 law ("boson peak"), the sound velocity shows a negative dispersion in the boson-peak frequency regime, and there is a strong increase in the sound attenuation near the boson-peak frequency. A generalized elasticity theory is presented, based on the model assumption that the shear modulus of the disordered medium fluctuates randomly in space. The fluctuations are assumed to be uncorrelated and have a certain distribution (Gaussian or otherwise). Using field-theoretical techniques one is able to derive mean-field theories for the vibrational spectrum of a disordered system. The theory based on a Gaussian distribution uses a self-consistent Born approximation (SCBA),while the theory for non-Gaussian distributions is based on a coherent-potential approximation (CPA). Both approximate theories appear to be saddle-point approximations of effective replica field theories. The theory gives a satisfactory explanation of the vibrational anomalies in glasses. Excellent agreement of the SCBA theory with simulation data on a soft-sphere glass is reached. Since the SCBA is based on a Gaussian distribution of local shear moduli, including negative values, this theory describes a shear instability as a function of the variance of shear fluctuations. In the vicinity of this instability, a fractal frequency dependence of the density of states and the sound attenuation ∝ ω1+a is predicted with a ≲ 1/2. Such a frequency dependence is indeed observed both in simulations and in experimental data. We argue that the observed frequency dependence stems from marginally stable regions in a glass and discuss these findings in terms of rigidity percolation. © 2013 EDP Sciences and Springer.
dc.publisherSpringer Nature
dc.titleVibrational anomalies and marginal stability of glasses
dc.typeArticle
dc.contributor.departmentPRIMALIGHT Research Group
dc.contributor.departmentElectrical Engineering Program
dc.contributor.departmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
dc.identifier.journalEuropean Physical Journal: Special Topics
dc.contributor.institutionUniv Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy
dc.contributor.institutionJohannes Gutenberg Univ Mainz, Inst Phys, D-55099 Mainz, Germany
kaust.personFratalocchi, Andrea
kaust.personMarruzzo, Alessia
dc.date.published-online2013-01-31
dc.date.published-print2013-01


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