LOCAL VIBRATIONAL DENSITIES OF STATES IN GLASSES - NUMERICAL STUDY OF A MODEL OF AMORPHOUS-SILICON

We analyze for the first time the relation between the shape of the local vibrational densities of states (LDOSs) and the local environments of atoms in glasses. We calculated the LDOSs in model silicon glasses by use of a recursion method. The glasses are produced by a constant pressure molecular dynamics method with a three-body potential by Stillinger and Weber. The transverse optic (TO) peaks reduce in height with an increase of the number of the coordinated atoms. The heights of the TO peaks also decrease with the increase of the number of the coordinated atoms that have (2,3,0) Voronoi signature. The heights of the transverse acoustic peak are insensitive to the number of bonds. The origin of the decrease of the TO peak is discussed. The slopes of the low frequency side of the LDOSs are insensitive to the local structure of the glasses. The long-range force field in the present glass is the same as that in the crystal state.