Ab Initio Construction of Interatomic Potentials for Uranium Dioxide Across all Interatomic Distances

TL;DR

This paper introduces a comprehensive methodology for constructing interatomic potentials for uranium dioxide that are valid across all energy and distance scales, improving the accuracy of molecular dynamics simulations.

Contribution

A new formalism that creates unified interatomic potentials over all length scales by combining a charged-ion model with ab initio data fitting.

Findings

Potential accurately models interactions from lattice vibrations to high-energy collisions.

Method successfully applied to uranium dioxide, capturing a wide range of conditions.

Eliminates ambiguity in potential construction across different atomic phenomena.

Abstract

We provide a methodology for generating interatomic potentials for use in classical molecular dynamics simulations of atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high energy collisions. A rigorous method to objectively determine the shape of an interatomic potential over all length scales is introduced by building upon a charged-ion generalization of the well-known Ziegler-Biersack-Littmark universal potential that provides the short- and long-range limiting behavior of the potential. At intermediate ranges the potential is smoothly adjusted by fitting to ab initio data. Our formalism provides a complete description of the interatomic potentials that can be used at any energy scale, and thus, eliminates the inherent ambiguity of splining different potentials generated to study different kinds of atomic materials behavior. We exemplify the method by developing rigid-ion potentials for uranium dioxide interactions under conditions ranging from thermodynamic equilibrium to very high atomic energy collisions relevant for fission events.