Infrared absorption in glasses and their crystalline counterparts

It is demonstrated by means of numerical analysis that absorption of light in glasses in the IR region, [Formula: see text], can be understood in terms of light absorption in their crystalline counterparts. This signifies the important role of local structural motifs (units) present both in glasses and crystals. Decomposition of the coupling coefficient into coherent and incoherent contributions gives insight into the origin of the spectral features of IR absorption. The analysis has been undertaken for classical molecular dynamics models of vitreous silica and its crystalline counterpart, α-cristobalite.