Bilayer representation 1 (BR1). For each bilayer A-B we created two data records. One record has layer A descriptors concatenated to layer B descriptors and the other has layer B descriptors concatenated to layer A descriptors. This method of representing multiple representations of the same data item has been previously applied to organic molecules. Using this representation for the prediction of d generates a data set with 482 = 267 × 2 -52 records (52 records are subtracted, instead of 53, because we have removed the PdS 2 |PdS 2 bilayer from the data set due to the appearance of covalent interaction between the S atoms of the adjacent layers). For the prediction of the band gap it generates 78 = 49 × 2 -20 records.