′�?, that has a frequency of 295 cm−1, is attributed for the stretching vibration of Ga–Se bonds. The 2-phonon absorption of the 295 cm−1 phonon corresponds to the crystal IR absorption edge, rather then the residual absorption peak. Density practical theory computations demonstrate the residual absorption on the BGSe crystal https://baga4se7crystal86296.blogoxo.com/32590000/baga4se7-crystal-options