The compressed directory data.tar.gz contains different folders that correspond to the various Figures of the article "First principles modeling of exciton-polaritons in polydiacetylene chains" (apart from Figures 1,2,4,6,9 which are schematics). These folders contain plan text .dat files with all the data necessary to reproduce the figures. The x-axis values are given in the first column of the .dat files, while the y-axis values are generally given in the 2nd column. Each figure subdirectory contains a README file with more information on the units of the physical quantities, and a more detailed description.

Briefly, the figure contents are as follows:

Figure 3: Experimental reflectivity and absorption spectra of the two variants of polydiacetylene crystals. Figure 5: Theoretical estimate of the imaginary part of the dielectric response of two real and two model PDA systems, obtained from GW-BSE calculations. Figure 7: (a) Polariton dispersion of the model blue PDA system, as obtained from our presented methodology. (b) The associated reflectance of this systems. Figure 8: Group velocity of the lower polariton band of the model blue PDA system, for different incident photon energies. Figure 10: Dependence of the exciton energy and the stop-band width on the number of diacetylene monomers of a polymer chain. Figure 11: The effect of vibrations on the (a) imaginary and (b) real parts of the dielectric response of the model blue PDA system. The associated reflectance is given in Figure (c). Figure 12: Dependence of Delta_vib on the exciton coherence length for the two model PDA systems. Figure 13: Dependence of Delta_vib on the width gamma of the exciton and vibronic peaks in the absorption spectrum.