Here, using self-consistent ab initio lattice dynamical calculations that go beyond the quasiharmonic approximation, we show that the high-pressure high-temperature bcc-Fe phase is dynamically stable. In this treatment the temperature-dependent phonon spectra are derived by exciting all the lattice vibrations, in which the phonon-phonon interactions are considered. The high-pressure and high-te...

Phonon thermal properties of graphene on hexagonal boron nitride are investigated by the molecular dynamics simulations combined with lattice dynamics theory. It is found that the dispersion curves have minor changes for supported graphene because the interlayer coupling is too weak to shift the harmonic phonon properties. The ZA and ZO phonon lifetimes are significantly reduced in supported gr...

In this paper, thermal conductivity of crystalline GaAs is calculated using first-principles lattice dynamics. The harmonic and cubic force constants are obtained by fitting them to the forcedisplacement data from density functional theory calculations. Phonon dispersion is calculated from dynamical matrix constructed using the harmonic force constants and phonon relaxation times are calculated...

We investigate the role of rattling guest atoms on the lattice thermal conductivity of a type-I clathrate Ba_{8}Ga_{16}Ge_{30} by first-principles lattice dynamics. Comparing phonon properties of filled and empty clathrates, we show that rattlers cause tenfold reductions in the relaxation time of phonons by increasing the phonon-phonon scattering probability. Contrary to the resonant scattering...

Black phosphorus attracts enormous attention as a promising layered material for electronic, optoelectronic and thermoelectric applications. Here we report large anisotropy in in-plane thermal conductivity of single-crystal black phosphorus nanoribbons along the zigzag and armchair lattice directions at variable temperatures. Thermal conductivity measurements were carried out under the conditio...

Recent studies of the surface dynamics of Al(001) and Cu(111) based on density functional perturbation theory have substantiated the existence of subsurface optical phonon resonances of all three polarizations, thus confirming early predictions of the embedded-atom method. The hybridization of the shear-vertical optical resonance with the longitudinal acoustic phonon branch accounts for the ubi...

In an attempt to provide a clearer understanding of the impressive increase in Tc under pressure in elemental Li, linear response calculation of the phonon dispersion curves, electron-phonon matrix elements, phonon linewidths and mode λ’s have been carried out on a finer mesh (24 in the Brillouin zone) than done previously, for the volume corresponding to 20 GPa pressure. The result illustrates...

The combined effects of strain and phonon confinement are seen to explain why the Raman peak near 464 cm in CeO22y nanoparticles shifts to progressively lower energies and the lineshape of this feature gets progressively broader and asymmetric ~on the low-energy side! as the particle size gets smaller. The increasing lattice constant measured for decreasing particle size explains this Raman shi...

We investigate the generation of acoustic phonons from electrostriction of optical waves in small core waveguides. We specifically consider simple step-index strip waveguides composed of silica or silicon in air, with sub-micron lateral dimensions. Such waveguides support one or a few optical modes, but a rich spectrum of acoustic phonons that becomes densely populated as the phonon frequency i...

The thermal conductivity of boron arsenide (BAs) is believed to be influenced by phonon scattering selection rules due its special dispersion. Compression BAs leads significant changes in dispersion, which allows for a test first principles theories how dispersion affects three- and four-phonon rates. This study reports the from 0 30 GPa. Thermal vs. pressure measured time-domain thermoreflecta...