Renormalized Phonon Microstructures at High Temperatures from First-Principles Calculations: Methodologies and Applications in Studying Strong Anharmonic Vibrations of Solids

Figure 4

Two-phonon density of states of rutile for 0 K and 800 K. The arrowheads mark the positions of the three Raman modes, , , and , respectively. The upconversion and downconversion contributions at 800 K are shown in green and black dashed curves, respectively. There is no upconversion process at 0 K. The phonon DOS spectra are presented along with the TDOS but take a negative sign and shaded blue to make the view of TDOS and DOS separated.