An investigation into the structural stabilities and the electronic and optical properties of $\mathrm{Ca}{\mathrm{F}}_2$ under high pressure was conducted using first-principles calculations based on density functional theory. Our results demonstrate that the sequence of the pressure-induced phase transition of $\mathrm{Ca}{\mathrm{F}}_2$ is the fluorite structure $\left(Fm3m\right)$, the $\mathrm{Pb}{\mathrm{Cl}}_2$-type structure $\left(Pnma\right)$, and the ${\mathrm{Ni}}_2\mathrm{In}$-type structure $(P{6}_3∕mmc)$. At these phase transformations, the coordination number of ${\mathrm{Ca}}^{2+}$ increases from eight to nine and then to eleven. The mechanisms of the structure change were revealed from the $\mathrm{Pb}{\mathrm{Cl}}_2$-type phase to the ${\mathrm{Ni}}_2\mathrm{In}$-type phase. The energy band gap increases with pressure in the $Fm3m$ and the $Pnma$ phases, but decreases in the $P{6}_3∕mmc$ phase. The band gap pressure coefficients were obtained using a linear pressure-dependent fit function. In addition, the energy band overlap metallization does not occur up to $218\mathrm{GPa}$. The static dielectric constants ${\epsilon }_0$ vs pressure are also discussed.

• Received 26 November 2005

DOI:https://doi.org/10.1103/PhysRevB.73.134103