Benchmarking of fast and interpretable UF machine learning potentials

Abstract

Machine learning interatomic potentials (MLIPs) have emerged as a powerful alternative to density functional theory (DFT) for molecular dynamics simulations, offering near-DFT accuracy at a fraction of the computational cost. However, many state-of-the-art MLIPs remain computationally demanding and act as black boxes, limiting physical interpretability. In this work, we evaluate the ultra-fast force field (UF 3 ) potential, which employs linear regression with a cubic B-spline basis to represent effective two- and three-body interactions. We show that UF 3 displays accuracy comparable to established models such as GAP, MTP, NNP (Behler–Parrinello), and qSNAP MLIPs. We further investigate the transferability of UF 3 by computing melting points for six elemental systems with potentials fitted without any solid–liquid interface configurations or explicit thermodynamic information about melting. The model reproduces experimental melting points within ∼ 6% for simple metals (Ni, Cu, Li), but substantially underestimates them for Mo and Si and fails to yield a stable potential for Ge, reflecting the limitations of a fixed expansion truncated at the three-body term for systems with strong angular or covalent bonding. We further illustrate how UF 3 ’s spline-based formulation allows direct visualization of the learned interactions, enabling identification of unphysical behavior that black-box approaches often obscure.