强电子-声子耦合助力Ag3模式蓝移：薄SnS薄片中扶手椅方向的独特效应

Due to the spontaneous polarization along the 'armchair' direction in the thin SnS film, a certain degree of electron-phonon coupling along the 'armchair' direction is expected, which will help the significant blue shift of the Ag3 mode as the film thickness gradually becomes thinner.