Ab initiocalculation of lattice dynamics in BeO

Abstract

Ground state lattice vibrational properties of wurtzite-BeO are reported using an ab initio plane-wave pseudopotential method. The ab initio results for the phonon dispersion relations are in good agreement with the available experimental data. The only discrepancy observed between experiment and present data for the longitudinal optic frequency at the centre of the Brillouin zone for a displacement along the symmetry axis is expected to be due to the indirect measurement of that mode in the experiment. The dielectric constant, the Born effective charges and the elastic constants for the compound are computed from the lattice dynamics. All of them agree well with the experimental results. The elastic constants calculated using the phonon spectra agree reasonably well with the results from other first-principles calculations. The good agreement of the quantities calculated, with the experimental results pave the way for future studies on the contribution of lattice vibrations to the pressure-induced phase transition in this compound. We try to understand the features of the phonon spectra from the component-projected phonon densities of states and by analysing the contributions of each atom type towards each normal mode. We find that the phonon spectra of BeO contains features common to some of the members with the same crystal structure as well as to some of the members in the same alkaline earth oxide group.

Dynamical stability and phase transition of BeO under pressure

“…[13][14][15][16] Our result is close to the latest generalized gradient approximation result of Cai et al 16 ͑105 GPa͒. 9 Thus, we see that phonon instability is taking place in BeO at a pressure much higher than that predicted from enthalpy calculations. 35 No attempt has been made so far to understand this pressure induced phase transition in beryllium oxide from lattice dynamics.…”

Dielectric Barrier, Etch Stop, and Metal Capping Materials for State of the Art and beyond Metal Interconnects

“…420 This is most likely due to the absence of p-orbitals for Be and similar electronegativity to O that results in the formation of short Be-O bonds and a dense covalent atomic structure. 421 Unfortunately, this dense atomic structure also results in BeO exhibiting a relatively high k with values of ∼6.8 being reported for ALD BeO thin films. 413 However, the dense atomic structure remains attractive for DB applications with thickness targets <2 nm.…”

“…414,422 Early interest in beryllium nitride and carbide compounds was primarily for nuclear applications, 421,423 with a few recent investigations focused on Be 3 N 2 and Be 2 C compounds as super hard semiconducting materials. 422,424 For Be 3 N 2 , theoretical investigations of the electronic structure for Be 3 N 2 do indicate a relatively dense atomic structure.…”

Ab initio molecular dynamics study of high-pressure melting of beryllium oxide

“…Song et al 20 and Zhang et al 21 took into account the effect of lattice vibrations to study the structural stability and phase transformation of BeO based on the mean-field-potential approach. The dispersion relations of BeO were measured by x-ray scattering experiment 22 and predicted by density functional perturbation theory 23 . Wdowik et al 24 and Luo et al 25 calculated the phase diagram and thermal properties of BeO within the quasiharmonic approximation.…”