Universality of the Nonphononic Vibrational Spectrum across Different Classes of Computer Glasses

D Richard and K Gonzalez-Lopez and G Kapteijns and R Pater and T Vaknin and E Bouchbinder and E Lerner, PHYSICAL REVIEW LETTERS, 125, 085502 (2020).

DOI: 10.1103/PhysRevLett.125.085502

It has been recently established that the low-frequency spectrum of simple computer glass models is populated by soft, quasilocalized nonphononic vibrational modes whose frequencies omega follow a gapless, universal distribution D(omega) similar to omega(4). While this universal nonphononic spectrum has been shown to be robust to varying the glass history and spatial dimension, it has so far only been observed in simple computer glasses featuring radially symmetric, pairwise interaction potentials. Consequently, the relevance of the universality of nonphononic spectra seen in simple computer glasses to realistic laboratory glasses remains unclear. Here, we demonstrate the emergence of the universal omega(4) nonphononic spectrum in a broad variety of realistic computer glass models, ranging from tetrahedral network glasses with three-body interactions, through molecular glasses and glassy polymers, to bulk metallic glasses. Taken together with previous observations, our results indicate that the low-frequency nonphononic vibrational spectrum of any glassy solid quenched from a melt features the universal omega(4) law, independently of the nature of its microscopic interactions.

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