Voronoi-Delaunay analysis of normal modes in a simple model glass

Article

关键词: FREQUENCY VIBRATIONAL-MODES;    VITREOUS SILICA;    BOSON PEAK;    AMORPHOUS-SILICON;    EXCITATIONS;    LIQUID;    LOCALIZATION;    SCATTERING;    DYNAMICS;    ALLOYS;   

DOI  :  10.1103/PhysRevB.62.3181

来源: SCIE

【 摘 要 】

We combine a conventional harmonic analysis of vibrations in a soft-sphere glass with a Voronoi-Delaunay geometrical analysis of the structure. Structure potentials (tetrahedricity, sphericity, or perfectness) are introduced to describe the shape of the local atomic configurations (Delaunay simplices) as a function of the atomic coordinates. Apart from the highest and lowest frequencies the amplitude weighted structure potential varies only little with frequency. The movement of atoms in soft vibrational modes causes transitions between different ''perfect'' realizations of local structure. As for the potential energy a dynamic matrix can be defined for the structure potential. Its expectation value with respect to the vibrational modes increases nearly linearly with frequency and shows a clear indication of the boson peak. The structure eigenvectors of this dynamical matrix are strongly correlated to the vibrational ones. Four subgroups of modes can be distinguished.

【 授权许可】

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