File Name : fig.s1.tif

Caption : fig. s1. the phonon dispersion curves of (a) fdd2 at 200 gpa and (b) is r-3 at 0 gpa.

File Name : fig.s2.tif

Caption : fig. s2. md simulation under 300, 1000 and 1500 k for p41212 and fdd2 structures. (a), (b) and (c) are p41212 energy-time steps. (d), (e) and (f) are fdd2 energy-time steps.

File Name : fig.s3.tif

Caption : fig. s3. md simulation at 300, 1000 and 1500 k and a fixed volume correspond a cold pressure of 200 gpa for fdd2 and 300 gpa for r-3 structure. (a), (b) and (c) are fdd2 energy-time steps. (d), (e) and (f) are r-3 energy-time steps. (g), (h) and (i) are snapshots of the final frame of fdd2 at 300 k, 1000 k and 1500 k at the end of 10 ps md simulations, and (j), (k) and (l) are that of r-3.