′�?, with a frequency of 295 cm−1, is attributed to your stretching vibration of Ga–Se bonds. The 2-phonon absorption from the 295 cm−1 phonon corresponds to the crystal IR absorption edge, rather than the residual absorption peak. Density functional theory computations clearly show the residual absorption of the BGSe crystal https://felixcfeda.wssblogs.com/32754252/the-smart-trick-of-baga4se7-crystal-that-nobody-is-discussing