Metropolis Dissertation Award: It's Not a S(KZ)CAM! Accurate Surface Modeling at Low Cost

Reactions supported on solid surfaces form the cornerstone of both the chemical and energy industries. With computational modeling, it is possible to attain an atomistic-level understanding of these processes, paving the way towards designing improved materials. However, reproducing experimental results remains challenging: density functional theory (DFT) is efficient but can be inconsistent, and while high-level quantum chemistry methods — notably the "gold-standard" coupled cluster theory [CCSD(T)] — can reach the required accuracy, their application to surfaces has been limited by prohibitively high costs.

I will present the SKZCAM (pronounced "scam") protocol, which overcomes this cost-accuracy tradeoff, enabling CCSD(T) for the surfaces of ionic materials at a cost approaching DFT. With the SKZCAM protocol, I have successfully resolved the adsorption energy — a key property governing catalytic and gas storage performance — for carbon monoxide on the MgO surface, a longstanding challenge for theory to get right. More recently, I have leveraged its low cost to study a diverse set of 19 molecules on technologically important surfaces such as MgO and TiO2, reproducing experimental adsorption energies while providing new understanding of their adsorption mechanisms. For example, I show that nitric oxide forms covalently bound dimers on the MgO surface, reconciling previously conflicting DFT interpretations and providing new insights on how this waste gas can be stored.

Beyond new atomistic insights, it is now possible to generate large reference-quality datasets of adsorption energies with the SKZCAM protocol, currently lacking within the research community. Using these datasets, I have explained why DFT predicts incorrect properties of gold nanoparticles on MgO, a model catalyst for carbon monoxide oxidation/removal in car exhausts, and proposed new cost-effective strategies to address these limitations of DFT. Finally, the SKZCAM protocol is now available as an open-source package, allowing the broader research community to build on these developments to explore more complex surface phenomena.