Figure 2

Experimental (bottom)59 and calculated (middle and top)61 INS spectra of the monoclinic (P21/a) phase of melamine. The most prominent experimental bands are denoted by Roman numerals. The shaded spectral regime highlights out-of-plane deformations of the hydrogen-bonded species. See the main text for numerical details and the Supplementary Information (Table S2 and Figs. S5–S15) for a detailed assignment and visualization of associated vibrations.