Fig. 1: Temperature dependence of the zone centre optical phonon frequencies. | npj Computational Materials

Fig. 1: Temperature dependence of the zone centre optical phonon frequencies.

From: The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

Fig. 1

a The lower transverse optical (TO) mode (E) and b the higher TO mode (A1) at the zone centre as we approach q = 0 along the X − Γ direction, perpendicular to the trigonal axis. Red circles and blue squares represent the calculated temperature-dependent effective potential (TDEP) and anharmonic phonon frequencies, while other symbols represent the experimental results from refs. 43,45,48. The TDEP frequency is the square root of the eigenvalue of the dynamical matrix at a particular temperature, while the anharmonic frequency is the peak of the phonon mode power spectrum. The black vertical line represents the phase boundary between the rhombohedral and rocksalt structures in our calculations (≈634 K).

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