We benchmark the effect of renormalization for three materials: ZrO 2 , GeTe, and Zr. The tetragonal-to-cubic transition of ZrO 2 occurs at a very high temperature of 2650 K , and the harmonic phonon dispersion of cubic ZrO 2 at 0 K shows severe instability with very negative imaginary modes as shown in Figure . As we increase the renormalization temperature, we find the imaginary phonon modes at the X point turning real at 2500 K, which is very close to the experimental transition temperature of 2650 K. However, as we discuss in more detail later, phonons becoming real is a necessary but not sufficient condition for the phase's manifestation. In GeTe, a semiconductor that exhibits a reversible phase transition between a rhombohedral and cubic structure, our results indicate the imaginary modes of the cubic phase at the Γ point vanishing around 400 K. However, the cubic phase does not manifest experimentally until 650 ± 100 K . In BCC Zr, we find the imaginary modes around the N point becoming real at around 700 K, but the experimental HCP-to-BCC phase transition temperature is much higher at around 1135 K . For a phase to manifest, it must not only be dynamically stable (real phonons) but also have the lowest free energy among all competing phases. This is investigated in the next section.