  Though extensively studied since the emergence of zincblende cubic A(B,C)
semiconductor alloys (zb-SCA) in the sixties, the phonon mode behavior of
Ga(As,P) remains a subject of debate to this day. Recently Zollner and
co-authors reported on a thorough far-infrared (IR) ellipsometry study of the
vibrational spectra of Ga(As,P) spanning the composition domain. They suggest
that their experimental data are better described by the cluster model than by
our percolation model. On the basis of Zollner experimental data, kindly made
available to us, we derive an improved version of the percolation model that
explains the phonon mode behavior of Ga(As,P) beyond existing CM and PM
approaches, with ab initio phonon calculations in support.
