Fig. 6.

Temperature dependence of the mobility of two different hcp–liquid planar interfaces with orientations (0001) and $\left(11\overline{2}0\right)$ at pressure $P=80$ GPa and $T_m=\mathrm{3,497}$ K. The calculations are performed in periodic slab geometries, with dimensions specified in SI Appendix. The (0001) interface kinetics is partitioned into three temperature regimes. 1) $T<\mathrm{3,489}$ K (green solid line with filled circles): The liquid phase transforms to the fcc phase, which grows on the hcp substrate. 2) $\mathrm{3,489}\le T\le \mathrm{3,503}$ K (green dashed line with open circles): No steady-state interface motion is observed. The hcp substrate interfaces the liquid through a film of fluctuating fcc clusters. 3) $T\ge \mathrm{3,503}$ K (red solid line with filled circles): The hcp slab melts at steady rate.