Phonon spectra of the high-frequency modes in dilute nitride random GaN$_x$As$_{1-x}$ alloy

The broadening of the highly localized isolated vibrational mode in GaNAs has been studied using the force constants between nearest-neighbor and second-nearest neighbor nitrogen pairs obtained from density functional theory supercell calculations. The phonon spectra of the high-frequency modes associated with substitutional nitrogen atoms in the random alloy are calculated for different nitrogen concentrations.