  The structural and dynamic properties of silica melts under high pressure are
studied using molecular dynamics (MD) computer simulation. The interactions
between the ions are modeled by a pairwise-additive potential, the so-called
CHIK potential, that has been recently proposed by Carre et al. The
experimental equation of state is well-reproduced by the CHIK model. With
increasing pressure (density), the structure changes from a tetrahedral network
to a network containing a high number of five- and six-fold Si-O coordination.
In the partial static structure factors, this change of the structure with
increasing density is reflected by a shift of the first sharp diffraction peak
towards higher wavenumbers q, eventually merging with the main peak at
densities around 4.2 g/cm^3. The self-diffusion constants as a function of
pressure show the experimentally-known maximum, occurring around a pressure of
about 20 GPa.
