Ground-state and lattice dynamical properties of BeS in the zinc-blende and nickel arsenide phases

Structural, elastic and dynamical properties of the zinc-blende and nickel arsenide structures of BeS have been studied by employing an ab initio pseudopotential method and a linear response approach, within the local density approximation. Our results compare quite well with the available experimental data. To the best of our knowledge, the elastic and lattice dynamical properties for BeS in the nickel arsenide phase are reported in the present study for the first time. Differences in the phonon spectra and density of states both in the acoustic and optical ranges between the two phases of interest are investigated. The linear and quadratic pressure coefficients of phonon frequencies at the center of the Brillouin zone are determined from the pressure dependence of vibration modes.

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