Dynamics of SiO$_2$ glasses

C. Oligschleger

Published 1998-12-15Version 1

Results on the dynamics of silica are presented: vibrations and relaxations. Using molecular dynamics, glass structures are generated by rapidly quenching melts below the glass transition. For the local minima of the structures the vibrational density of states is determined, the structures of the eigenmodes are analyzed, and the influence of the single components is discussed. Relaxations are studied in both amorphous SiO$_2$ and silica melts. Our main focus is on the type of relaxation, i.e., whether the main contributions are caused by small atomic displacements, or by bond-breaking processes, e.g. creation and annihilation of dangling bonds. The eigenvector of the relaxations is found to be similar to the low-frequency one.