The effect of topological local order on vibrational dynamics in simple one-component glasses is analyzed numerically. The vibrational density of states of a glass with icosahedral local order is found to be similar to that of the sigma -phase, a Frank-Kasper crystal, which represents a counterpart periodic phase for this glass. Optic-like longitudinal vibrational modes and two incommensurate length scales having analogues in the sigma -phase are observed in this glass. This pattern of vibrational dynamics is in contrast with that generally ascribed to simple one-component glasses: e.g. a Lennard-Jones (LJ) glass is characterized by a single length scale and supports only modes with acoustic behavior. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 20]
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