In addition to the unknown direction of the polarization with respect to the crystal axes, there are other factors, both on the experimental side and on the theoretical side that can contribute to discrepancies. In ref. the crystal structure of the films is not reported. The crystal structures used in our calculations are the common forms of p-terphenyl and chrysene, but both materials have other polymorphs reported in the CSD (for triphenylene all CSD entries appear to be the same structure but we cannot rule out the appearance of a different thin film polymorph). In polycrystals there can be contributions from grain boundaries (in samples comprising very small crystallites, which is not the case here, there can be surface contributions as well).