  We investigate phonon transport in perovskite strontium titanate (SrTiO3)
which is stable above its phase transition temperature (~105 K) by using
first-principles molecular dynamics and anharmonic lattice dynamics. Unlike
conventional ground-state-based perturbation methods that give imaginary phonon
frequencies, the current calculation reproduces stable phonon dispersion
relations observed in experiments. We find the contribution of optical phonons
to overall lattice thermal conductivity is larger than 60%, markedly different
from the usual picture with dominant contribution from acoustic phonons. The
mode- and pseudopotential-dependence analysis suggests the strong attenuation
of acoustic phonons transport originated from strong anharmonic coupling with
the transversely-polarized ferroelectric modes.
