  The structure of surfaces and interfaces of silica (SiO2) is investigated by
large scale molecular dynamics computer simulations. In the case of a free
silica surface, the results of a classical molecular dynamics simulation are
compared to those of an ab initio method, the Car-Parrinello molecular
dynamics. This comparative study allows to check the accuracy of the model
potential that underlies the classical simulation. By means of a pure classical
MD, the interface between amorphous and crystalline SiO2 is investigated, and
as a third example the structure of a silica melt between walls is studied in
equilibrium and under shear. We show that in the latter three examples
important structural information such as ring size distributions can be gained
from the computer simulation that is not accessible in experiments.
