The shock-induced phase transition of a ${\mathrm{MgF}}_2$ crystal with the rutile structure was simulated by means of a molecular-dynamics (MD) calculation, where the simplified interatomic potential function was applied. We found that the rutile structure of a ${\mathrm{MgF}}_2$ crystal is transformed to the cubic fluorite structure in several femtoseconds through both the static and the biaxial shock-compression processes of the MD calculation, in which the transition pressure at room temperature was successfully reproduced. Moreover, we revealed explicitly that the mechanism of the rutile-cubic phase transition is mainly due to the rotational motion of ${\mathrm{F}}^{\mathrm{-}}$ ions surrounding the ${\mathrm{Mg}}^{2+}$ ion in the crystal.

• Received 17 April 1995

DOI:https://doi.org/10.1103/PhysRevB.52.3170