Origin of anomalous anharmonic lattice dynamics of lead telluride

The origin of the anomalous anharmonic lattice dynamics of lead telluride is investigated by molecular dynamics simulations with interatomic force constants (IFCs) obtained up to quartic terms from first principles. The calculations reproduce the asymmetry of the radial distribution function and the double peaks of transverse optical phonon previously observed with neutron diffraction and scattering experiments. They are identified to be due to the extremely large nearest-neighbor cubic IFCs in the [100] direction. The outstanding strength of the nearest-neighbor cubic IFCs, compared with the longer-range interactions, explains why the distortion in the radial distribution function is local. © 2014 The Japan Society of Applied Physics.