Figure 15: The theoretically derived 𝜈 O D band contours calculated in terms of the “strong-coupling” theory in the limits of the two different vibrational exciton coupling mechanisms involving the cyclic dimer hydrogen bonds, that is, “side-to-side” (SS) and “tail-to-head” (TH). (a) The SS coupling mechanism. (b) The TH coupling mechanism. (I) The “minus” band. (II) The “plus” band. (III) Superposition of the spectra I and II, each taken with its appropriate individual statistical weight parameter, 𝐹 and 𝐹 + . In both mechanism cases, the same coupling parameter value system was used for calculations: 𝑏 𝐻 = 0.7, 𝐶 0 = 0.7, 𝐶 1 = −0.2, 𝐹 + = 1.0, 𝐹 = 0.2, ΩOO = 100 cm−1. The transition frequencies are in the ω OO vibrational quantum units, and the transition frequencies are expressed with respect to the gravity center of the hypothetical spectrum of a monomeric hydrogen bond in the cyclic deuterium bond dimer. Transition intensities are in arbitrary units.