Atomic Permutation-Invariant Polynomials (aPIPs) for Materials and Molecules
Genevive Dusson (University of Warwick)

I will present the practical construction of interatomic potentials for materials and molecules based on a body-order expansion (ANOVA, HDRM), each body order being represented by polynomials satisfying the rotation and permutation symmetry of the "exact" potential energy surface. These polynomials are determined in a data-driven fashion from linear fits trained with ab initio data.
I will report convergence tests on training sets for materials and molecules, illustrating the accuracy, the low computational cost, and the systematic improvability of the potential. I will then outline a range of the regularisation procedures that we incorporate into the polynomial fits to achieve transferability of the potentials. Finally, I will outline a testing framework to stress-test the generalisation capabilities of new potentials far from the training set.
Joint work with Alice Allen (Cambridge), Gbor Csnyi (Cambridge), Christoph Ortner (Warwick), and Cas van der Oord (Cambridge).