Strain influence on III-nitrides: Ab initio studies of structural, lattice-dynamical, and dielectric properties

We present results of first-principles calculations concerning structural, dielectric, and lattice-dynamical properties of strained GaN and AlN in wur tzite structure. In particular, we consider the symmetry-conserving biaxial strain along the c-axis. Its influence on the lattice parameters, the diel ectric constants, the dynamical effective charges, and the phonon frequenci es is studied in detail. In addition, we investigate the variation of the d ielectric and lattice-dynamical properties with the internal strain.