6533b86efe1ef96bd12cc7fa
RESEARCH PRODUCT
Harmonic Vibrational Excitations in Disordered Solids and the "Boson Peak"
Walter SchirmacherCarl GanterGregor Diezemannsubject
PhysicsCondensed matter physicsCondensed Matter (cond-mat)FOS: Physical sciencesGeneral Physics and AstronomyCondensed MatterInstabilityStability (probability)OmegaHarmonicDensity of statesCoherent potential approximationBoson peakHarmonic oscillatordescription
We consider a system of coupled classical harmonic oscillators with spatially fluctuating nearest-neighbor force constants on a simple cubic lattice. The model is solved both by numerically diagonalizing the Hamiltonian and by applying the single-bond coherent potential approximation. The results for the density of states $g(\omega)$ are in excellent agreement with each other. As the degree of disorder is increased the system becomes unstable due to the presence of negative force constants. If the system is near the borderline of stability a low-frequency peak appears in the reduced density of states $g(\omega)/\omega^2$ as a precursor of the instability. We argue that this peak is the analogon of the "boson peak", observed in structural glasses. By means of the level distance statistics we show that the peak is not associated with localized states.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1998-07-06 |