Enumerating low-frequency nonphononic vibrations in computer glasses

Fuente: arXiv
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Autores principales: Lerner, Edan, Moriel, Avraham, Bouchbinder, Eran
Formato: Preprint
Publicado: 2024
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author Lerner, Edan
Moriel, Avraham
Bouchbinder, Eran
author_facet Lerner, Edan
Moriel, Avraham
Bouchbinder, Eran
contents In addition to Goldstone phonons that generically emerge in the low-frequency vibrational spectrum of any solid, crystalline or glassy, structural glasses also feature other low-frequency vibrational modes. The nature and statistical properties of these modes -- often termed `excess modes' -- have been the subject of decades-long investigation. Studying them, even using well-controlled computer glasses, has proven challenging due to strong spatial hybridization effects between phononic and nonphononic excitations, which hinder quantitative analyses of the nonphononic contribution ${\cal D}_{\rm G}(ω)$ to the total spectrum ${\cal D}(ω)$, per frequency $ω$. Here, using recent advances indicating that ${\cal D}_{\rm G}(ω)\!=\!{\cal D}(ω)-{\cal D}_{\rm D}(ω)$, where ${\cal D}_{\rm D}(ω)$ is Debye's spectrum of phonons, we present a simple and straightforward scheme to enumerate nonphononic modes in computer glasses. Our analysis establishes that nonphononic modes in computer glasses indeed make an additive contribution to the total spectrum, including in the presence of strong hybridizations. Moreover, it cleanly reveals the universal ${\cal D}_{\rm G}(ω)\!\sim\!ω^4$ tail of the nonphononic spectrum, and opens the way for related analyses of experimental spectra of glasses.
format Preprint
id arxiv_https___arxiv_org_abs_2404_12735
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Enumerating low-frequency nonphononic vibrations in computer glasses
Lerner, Edan
Moriel, Avraham
Bouchbinder, Eran
Soft Condensed Matter
Disordered Systems and Neural Networks
In addition to Goldstone phonons that generically emerge in the low-frequency vibrational spectrum of any solid, crystalline or glassy, structural glasses also feature other low-frequency vibrational modes. The nature and statistical properties of these modes -- often termed `excess modes' -- have been the subject of decades-long investigation. Studying them, even using well-controlled computer glasses, has proven challenging due to strong spatial hybridization effects between phononic and nonphononic excitations, which hinder quantitative analyses of the nonphononic contribution ${\cal D}_{\rm G}(ω)$ to the total spectrum ${\cal D}(ω)$, per frequency $ω$. Here, using recent advances indicating that ${\cal D}_{\rm G}(ω)\!=\!{\cal D}(ω)-{\cal D}_{\rm D}(ω)$, where ${\cal D}_{\rm D}(ω)$ is Debye's spectrum of phonons, we present a simple and straightforward scheme to enumerate nonphononic modes in computer glasses. Our analysis establishes that nonphononic modes in computer glasses indeed make an additive contribution to the total spectrum, including in the presence of strong hybridizations. Moreover, it cleanly reveals the universal ${\cal D}_{\rm G}(ω)\!\sim\!ω^4$ tail of the nonphononic spectrum, and opens the way for related analyses of experimental spectra of glasses.
title Enumerating low-frequency nonphononic vibrations in computer glasses
topic Soft Condensed Matter
Disordered Systems and Neural Networks
url https://arxiv.org/abs/2404.12735