Electronic and Structural Properties of BeSe, BeTe, and BeS: Comparison between ab‐initio Theory and Experiments

Abstract

We have used first principles total energy pseudopotential techniques to calculate the ground state properties and the relative stabilities of the high pressure phases of the beryllium chalcogenides BeSe, BeTe, and BeS. We study the energy-volume (E-V) relations of the zincblende, NaCl, CsCl, NiAs, and P S n structures of these compounds. The components of the stress tensor were also calculated and used in the structural relaxation of the tetragonal and hexagonal phases. From the E-V curves of the structures considered and the Gibbs construction we find that these compounds transform under pressure from the zincblende structure (B3) to the NiAs structure (B8), and no further transitions are found. Our calculated values of the structural parameters and the B3 + B8 transition pressure for BeSe and BeTe agree well with recent experimental results. Very little is known experimentally for BeS, and our results for this compound have a predictive character.

Phase transformation of BeS and equation-of-state studies to 96 GPa

“…The calculated volume decrease at the transition was 10.9% while the measured value was 11.0%. Calculations by Muñoz and co-workers 30 give for the ZB phase It is of interest to compare the bulk moduli of the BeX compounds as shown in Table IV. There is a simple relation…”

Electronic excitations in beryllium chalcogenides from theab initioGWapproach

“…The LDA results are in good agreement with the previous ab initio calculations. [8][9][10] In Figs. 4, 5, and 6, the GW band structures along the LϪ⌫ϪX directions are shown.…”

“…Theoretically, there exists a nonrelativistic, self-consistent calculation of the band structure and the dielectric function of these compounds by Stukel, 8 using Slater's localexchange potential approach, and two recent nonrelativistic LDA calculations of their structural and electronic properties. 9,10 In order to comply with the renewed interest and to support the experiments with a theoretical database, we have performed a state-of-the-art ab initio calculation of the oneparticle excitation spectrum of the three beryllium chalcogenides. Besides the inclusion of many-body energy shifts and relativistic effects, we study in detail the dynamics of excited electrons and holes manifested in their lifetimes and the inelastic mean free paths.…”

High-pressure structural and optical properties of wurtzite-type Zn1−Mg Se

“…This change is due to a reduction of the average bond ionicity accompanied by increase of the cohesive energy from 1.3 to 2.2 eV/bond [28]. For the same reasons, the bulk modulus of BeSe containing alloy should markedly increase when creating (Zn,Mg,Be)Se by adding the BeSe component, because the bulk modulus of BeSe exceeds 90 GPa [26,29], i.e. it is by about 30 GPa higher than that for ZnSe.…”