  It is demonstrated that the width of the uncorrelated atomic-charge
distribution in glasses can be extracted from the frequency dependence of the
coupling coefficient for the far-infrared absorption measured experimentally by
the time-domain terahertz spectroscopy technique. This value for As2S3 glass is
found to be 0.12 (e). A density functional theory-based tight-binding molecular
dynamics model of As2S3 glass qualitatively supports these findings.
