′�?, with a frequency of 295 cm−1, is attributed for the stretching vibration of Ga–Se bonds. The two-phonon absorption from the 295 cm−1 phonon corresponds into the crystal IR absorption edge, instead of the residual absorption peak. Density functional principle computations present that the residual absorption of the BGSe crystal https://baga4se7crystal69024.anchor-blog.com/12946541/baga4se7-crystal-fundamentals-explained