Low-frequency Raman scattering in model disordered solids: percolators above threshold

TL;DR

This paper investigates low-frequency Raman scattering in disordered solids modeled as percolators above threshold, comparing two scattering mechanisms and finding that Bond Polarizability aligns better with experimental data.

Contribution

It computes Raman coupling coefficients for site- and bond-percolators using BPOL and DID mechanisms, revealing different low-frequency behaviors and validating BPOL against experiments.

Findings

DID does not follow a low-frequency scaling law.

BPOL frequency dependence agrees semi-quantitatively with experiments.

BPOL is a suitable scattering mechanism for modeling real glasses.

Abstract

The Raman coupling coefficients of site- and bond-percolators at concentration higher than percolation threshold are computed for two scattering mechanisms: Bond Polarizability (BPOL) and Dipole-Induced-Dipole (DID). The results show that DID does not follow a scaling law at low frequency, while in the case of BPOL the situation is less clear. The numerically computed frequency dependence in the case of BPOL, which can be considered a good scattering mechanism for a wide class of real glasses, is in semiquantitative agreement with experimental results.