Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices

Abstract In this work, the nature of the boson peak associated with the interaction between acoustic and optical phonons is revealed in low-density amorphous LDA ice and hexagonal crystalline ice (I h ) using the lattice dynamics method within the SPC/Emod water model. The appearance of these vibrat...

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Main Authors: Rodion V. Belosludov, Kirill V. Gets, Ravil K. Zhdanov, Yulia Y. Bozhko, Vladimir R. Belosludov
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-025-97595-y
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author Rodion V. Belosludov
Kirill V. Gets
Ravil K. Zhdanov
Yulia Y. Bozhko
Vladimir R. Belosludov
author_facet Rodion V. Belosludov
Kirill V. Gets
Ravil K. Zhdanov
Yulia Y. Bozhko
Vladimir R. Belosludov
author_sort Rodion V. Belosludov
collection DOAJ
description Abstract In this work, the nature of the boson peak associated with the interaction between acoustic and optical phonons is revealed in low-density amorphous LDA ice and hexagonal crystalline ice (I h ) using the lattice dynamics method within the SPC/Emod water model. The appearance of these vibrations is associated with proton disordering in ice I h and with both protons and oxygen atoms in LDA ice. Based on calculation of the eigenfrequencies and eigenvectors of vibrations, dispersion curves were constructed, the dynamics of water molecules involved in various vibrations was characterized, and the spatial molecular distribution was visualized. This enabled the identification of the structural inhomogeneities of the molecules participating in the vibrations. The presence of a boson peak in both amorphous LDA ice and crystalline ice I h and its relation to proton or molecular disorder are shown. The collective nature of the vibrations that form the boson peak is discussed. The distances between neighboring water molecules involved in high-amplitude boson peak vibrations in both LDA and Ih ices are below the average value and are located more closely to each other. Analysis of the obtained data showed that the appearance of the boson peak can be associated with the interaction of acoustic vibrations with the vibrations of structural inhomogeneities, which form low-energy optical vibrations. This paper shows for the first time a boson peak-like anomaly in the heat capacity of the structure of crystalline ice I h , as well as amorphous LDA ice. Our work confirms that the mechanism of formation of the boson peak is associated with acousto-optical resonance, leading to pseudo van Hove singularities of the acoustic phonon branches, and is also associated with the densification of low-frequency optical branches, which are quasi-degenerate with longitudinal acoustic vibrations, and leads to the appearance of excess low-frequency vibrations.
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spelling doaj-art-87c2d492822a4dc7bd1980d4705f8db52025-08-20T02:55:25ZengNature PortfolioScientific Reports2045-23222025-04-0115111410.1038/s41598-025-97595-yNature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA IcesRodion V. Belosludov0Kirill V. Gets1Ravil K. Zhdanov2Yulia Y. Bozhko3Vladimir R. Belosludov4Institute for Materials Research, Tohoku UniversityNikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of SciencesNikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of SciencesNikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of SciencesNikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of SciencesAbstract In this work, the nature of the boson peak associated with the interaction between acoustic and optical phonons is revealed in low-density amorphous LDA ice and hexagonal crystalline ice (I h ) using the lattice dynamics method within the SPC/Emod water model. The appearance of these vibrations is associated with proton disordering in ice I h and with both protons and oxygen atoms in LDA ice. Based on calculation of the eigenfrequencies and eigenvectors of vibrations, dispersion curves were constructed, the dynamics of water molecules involved in various vibrations was characterized, and the spatial molecular distribution was visualized. This enabled the identification of the structural inhomogeneities of the molecules participating in the vibrations. The presence of a boson peak in both amorphous LDA ice and crystalline ice I h and its relation to proton or molecular disorder are shown. The collective nature of the vibrations that form the boson peak is discussed. The distances between neighboring water molecules involved in high-amplitude boson peak vibrations in both LDA and Ih ices are below the average value and are located more closely to each other. Analysis of the obtained data showed that the appearance of the boson peak can be associated with the interaction of acoustic vibrations with the vibrations of structural inhomogeneities, which form low-energy optical vibrations. This paper shows for the first time a boson peak-like anomaly in the heat capacity of the structure of crystalline ice I h , as well as amorphous LDA ice. Our work confirms that the mechanism of formation of the boson peak is associated with acousto-optical resonance, leading to pseudo van Hove singularities of the acoustic phonon branches, and is also associated with the densification of low-frequency optical branches, which are quasi-degenerate with longitudinal acoustic vibrations, and leads to the appearance of excess low-frequency vibrations.https://doi.org/10.1038/s41598-025-97595-y
spellingShingle Rodion V. Belosludov
Kirill V. Gets
Ravil K. Zhdanov
Yulia Y. Bozhko
Vladimir R. Belosludov
Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices
Scientific Reports
title Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices
title_full Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices
title_fullStr Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices
title_full_unstemmed Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices
title_short Nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in Ih and LDA Ices
title_sort nature of boson peak and associated heat capacity anomaly caused by structural and proton disorder in ih and lda ices
url https://doi.org/10.1038/s41598-025-97595-y
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