“…In a ML potential, the site potential U i is not directly modeled as a function of the relative coordinates {r i j }, but as a function of a high-dimensional descriptor vector, whose components are invariant with respect to spatial translation, three-dimensional rotation and inversion, and permutation of atoms with the same species [30]. Many descriptors have been proposed, including, e.g., Behler's symmetry functions [31], the smooth overlap of atomic positions (SOAP) [30], the bispectrum [7], the Coulomb matrix [32], the moment tensor [17], the atomic cluster expansions [33], the embedded atom descriptor [34], the Gaussian moments [35], and the atomic permutationally invariant polynomials [36]. There are libraries implementing various descriptors [37][38][39].…”