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There is an evident misprint in the labeling of the Raman features in the first sentence of the first paragraph in the first column of page 165206-8. The correct sentence is: "Also, we identify the minor optical band detected by Lucovsky et al. in their pioneer IR measurements as the LO int. -TO Ga-P In band." This misprint does not change any of the conclusions of the paper.

We propose a simplified version of our 1-bond→2-mode percolation model initially developed for the q ~ 0 phonon properties of the stiff Be-VI bond in (Zn,Be)-chalcogenides, which open the class of random mixed crystals with contrast in the bond stiffness. The simplified version applies to the 'usual' alloys, i.e. made of soft-like bonds only. It is derived from detailed comparison of the Raman responses from the stiff Be-Te bond and the soft Zn-Te one in the pioneer (Zn,Be)Te system. The simplified version is eventually tested on (Ga,In)As whose 1-bond→2-mode behavior in the Ga-As range of the Raman spectra remains a much debated issue. Further, we lay the foundations for a comprehensive re-examination of the puzzling phonon behavior' of the similar (Ga,In)P alloy, by analogy with (Ga,In)As.

Contrary to a broadly accepted assumption we show that random (Ga,In)P is not an exception with respect to the crude classification of the phonon mode behavior of random mixed crystals in terms of 1-bond->1-mode systems or 2-bond->1-mode systems, as established from the simple criterion derived by Elliott et al. [Rev.Mod.Phys. 46, 465 (1974)]. Consistent understanding of the puzzling Raman/infrared behavior of (Ga,In)P, that has been a subject of controversy, is achieved via a basic version of our 1-bond->2-mode model. The Raman/infrared features from (Ga,In)P are accordingly re-assigned, with considerable change with respect to the previous approaches. Besides, we show that the idea of two bond lengths per species in alloys, supported by our 1-bond->2-phonon picture, opens an attractive area for the discussion of spontaneous ordering in GaInP_2, and in mixed crystals in general. The whole discussion is supported by detailed re-examination of the (Ga,In)P Raman/infrared data in the literature, full contour modeling of the transverse and longitudinal optical Raman lineshapes via our phenomenological 1-bond->2-mode model, and first-principles bond length calculations.Comment: 12 pages, 3 figures, submitted to Phys.Rev.