6533b85dfe1ef96bd12bdc21
RESEARCH PRODUCT
Model calculations for vibrational properties of disordered solids and the “boson peak”
Gregor DiezemannCarl GanterWalter Schirmachersubject
PhysicsCondensed matter physicsPhononDynamic structure factorScalar (physics)Condensed Matter PhysicsInstabilityElectronic Optical and Magnetic Materialssymbols.namesakeDensity of statessymbolsCoherent potential approximationElectrical and Electronic EngineeringHarmonic oscillatorDebyedescription
Abstract It is demonstrated that a disordered system of coupled classical harmonic oscillators with a continuous distribution of coupling parameters exhibits generally a low-frequency enhancement (“boson peak”) of the density of states, as compared with the Debye law. This phenomenon is most pronounced if the system is close to an instability. This is shown by means of a scalar model on a simple cubic lattice. The force constants are assumed to fluctuate from bond to bond according to a Gaussian distribution which is truncated at its lower end. The model is solved for the density of states and the one-phonon dynamic structure factor S(q, ω) by applying the two-site coherent potential approximation (CPA). The results for the density of states are in very good agreement with a numerical evaluation of the same model.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1999-03-01 | Physica B: Condensed Matter |