Computational approaches to materials design

New materials with properties tailored to specific applications often represent the heart of novel chemical processes and important technological advances. The fundamental understanding of the correlation between materials structure and properties is the key to designing new materials with the desired properties.

The primary focus of our research is on atomic-scale materials design, based on first-principles electronic structure calculations. We are applying state-of-the-art theoretical methods to study a range of surface phenomena including adsorption, diffusion and chemical reactions on a variety of catalytic and semiconductor surfaces.

These quantum chemical and solid-state physics methods take advantage of the impressive computational speed provided by arrays of fast workstations running in parallel both locally and at the national super-computer centers. Recent progress in theory allows approximate solutions to the electronic structure problem to be obtained with reasonable accuracy, compared to experimental data. As a result, we can now calculate good estimates for binding energies and diffusion barriers of atoms and molecules on, for example, transition metal surfaces. Moreover, site preferences, adsorbate interactions and the nature of specific bonds can all be investigated thoroughly and complement the information provided by advanced experimental techniques. Sophisticated computational algorithms allow determination of the detailed reaction paths connecting reactants and products of elementary reaction steps of important reaction schemes.

In the course of revealing all of this information at the atomic and molecular level, important reaction intermediates, often spectroscopically elusive, can be discovered, thus guiding new experimental efforts towards unexplored territory.

The detailed study of competing reaction paths, through the calculation of the corresponding activation energy barriers, allows for the isolation of electronic and geometric factors determining reaction selectivity in a way that is not accessible to experiments, where usually a set of overlapping factors act simultaneously.

Our general research strategy is to study trends in chemical reactivity of solid surfaces and identify discontinuities in their behavior. Explaining trends and discontinuities can help us understand the fundamental reasons behind changes in reactivity. We can then proceed, in strong interaction with experiments, to design surfaces characterized by the desired properties.

Currently, we are focusing on fundamental reactivity studies for a wide range of important applications, including: bimetallic catalysis, selective partial oxidation of hydrocarbons, fuel cells, and the development of novel low-temperature and environmentally benign catalytic processes. In order to meet the computational challenges posed by these projects, we are putting together one of the first "Beowulf" clusters in a chemical engineering department, which will allow us to perform high throughput parallel computing in-house.

By Manos Mavrikakis