  We study the static and dynamic properties of liquid silica over a wide range
of temperature T and density using computer simulations. The results reveal a
change in the potential energy landscape as T decreases that underlies a
transition from a fragile liquid at high T to a strong liquid at low T. We also
show that a specific heat anomaly is associated with this fragile-to-strong
transition, and suggest that this anomaly is related to the polyamorphic
behaviour of amorphous solid silica.
