Ab initio modeling of fused silica, crystal quartz, and water Raman spectra

Fused silica light-scattering properties are important for many industrial and laboratory applications. In this work, ab initio molecular dynamics employing periodic boundary conditions are used to simulate its structure and Raman scattering. Fused silica geometry is modeled as a frozen liquid, and the spectra are compared to those of crystal quartz. The method is tested also on Raman spectra of liquid water. Structural similarities between water and fused silica are discussed. The modeling agrees with experiment and suggests that most fused silica spectral features can be explained within the harmonic approximation. The combination of Raman spectroscopy with theoretical computations thus appears useful for structural studies of amorphous materials.