Boson peak and terahertz frequency dynamics of vitreous silica

This paper describes the progress that has been made in the past decade in the investigation of the peculiar dynamic properties of vitreous silica (v-SiO2) and related glasses in the terahertz (THz) frequency range. The reason why we focus our attention on v-SiO2 is that it is one of the principal network glasses and exhibits all features typical of glasses. These are the increased inelastic scattering of light and neutrons at THz frequencies, the so-called Boson or Bose peak, as well as unusual thermal properties such as specific heats and thermal conductivities at low temperatures. During the last decade, experimental techniques such as the inelastic scattering of light, neutrons and x-rays have been greatly improved, and these have provided considerable experimental information about the atomic vibrations in v-SiO2 and related glasses in the THz frequency region. In addition, molecular dynamics simulations have proved successful for these complex systems. They form the basis for this perspective on the major advances in this decade from a new and tutorial point of view.