In the difference plots (Figures ) the colored areas indicate prediction errors ranging from 1 (dark color) to 0.01 atomic units (bright color) -an error magnitude acceptable for NAMD simulations. Vice versa, gray color indicates prediction errors above 1 atomic unit reaching up to 100 atomic units (black). In the corresponding error difference plots, green highlights regions where PaiNN-based SpaiNN models yield predictions closer to the reference values compared to those based on SchNet, while pink indicates the opposite. We discuss the respective results for the selected NACs of the alkenes and CH 2 NH + 2 individually in the subsequent paragraphs.