Micro-to-macroscaling of DFT-calculated IR spectra for spectrum-feature extraction and estimation of dielectric response

Extraction of experimental spectrum features from target molecules, for purpose of their detection, can be achieved by comparison to template spectra within a database. This study continues presentation of the concept of using density functional theory (DFT). DFT-calculated spectra are well posed for comparison to measured spectra, to the extent of their scalability to larger space–time scales. Specifically, the focus of this study is the scalability of DFT-calculated IR spectra with respect to meso- and macroscales, characteristic of dielectric response as measured using different IR spectroscopies. A case-study analysis concerning IR spectra scalability for caffeine is described. Caffeine is only used as an example of analysis that can be applied to PFAS molecules, which are our major interest.