A novel approach for accurate orbital-free density functional theory calculations

Since the advent of density functional theory (DFT), accurately predicting the electronic structure of quantum systems without relying on Mermin-Kohn-Sham (MKS) orbitals remained an unresolved challenge. In this work, we introduce the new approach within the orbital-free DFT (OF-DFT) framework to advance this decades-long endeavor — modified Pauli potential density functional theory (MPP-OF-DFT). At the heart of our method lies the modified Pauli potential (MPP) - a quantity we define as a finite-T generalization of the Pauli potential through which all the effects tied to the Pauli exclusion principle are captured at zero-T. A comprehensive analysis of the MPP encompassing its interpretation from a fundamental physics perspective as well as its exact mathematical properties manifestly signal the presence of the conceptually rich and potentially field-shaping avenue of development. MPP-OF-DFT leverages a key observation: for a given element at fixed density and temperature conditions, MPP associated with the single atom exhibits highly isotropic behavior and remains invariant under changes in ionic configurations — effectively retaining its shape throughout the molecular dynamics (MD) simulation. This enables construction of the reusable orbital-based, and thus very accurate, MPPs which can then be deployed in OF-DFT calculations as needed.