Research

Computational study of plutonium dioxide surfaces

A density-functional-theory and atomistic-simulation study of actinide-oxide surfaces, focused on PuO₂: its bulk and surface properties, gas-adsorption mechanisms, and what they imply for long-term nuclear-waste storage safety.

Context

Plutonium dioxide is the principal long-lived component of stored spent nuclear fuel. Its behaviour at surfaces, how it interacts with water, hydrogen, and other ambient gases, drives the corrosion, radiolysis and gas-evolution processes that determine the safety margins of long-term storage. Despite its importance, accurate atomistic models of these surfaces remain difficult because the 5f electrons of plutonium make a standard DFT description awkward, and because experimental data on radioactive surfaces is sparse.

My research uses first-principles calculations to map the energetics and geometries of PuO₂ surfaces, predict how different molecular species adsorb and react on them, and benchmark the methodological choices that affect those predictions.

Approach

All calculations use density functional theory as implemented in VASP. The workflow:

The software I write, Bravais for interactive structure building and SURP for batch automation, exists to take the friction out of these steps. For the harder problem of placing many water molecules on a surface, I use a genetic algorithm driven by a surrogate energy and validated with DFT.

Details