Theory and Modeling

Group Leader: Stephen Gray

An exciting aspect of nanoscience is the close interplay between theory and experiment. In the Theory and Modeling Group, we focus on a number of specific, experimentally relevant areas including, but not limited to, nanocatalysis and nanophotonics. Our nanocatalysis work seeks to discover the key factors governing catalytic activity of nanoparticles with state-of-the-art electronic structure theory. This work enables, for example, efficient computational screening of large numbers of catalytic materials for which an experimental approach would be prohibitive. Our nanophotonics theory and modeling includes rigorous electrodynamics simulations to understand how light can be effectively manipulated in a variety of nanostructures. This work is of relevance to optoelectronics, chemical sensing, imaging, and solar energy applications.

Research in the above areas, including the tools and expertise developed, contribute to a larger plan for the Theory and Modeling Group. This larger plan involves establishment of a "Virtual Fab Lab" (VFL) for the theoretical prediction of nanoscale materials or devices with user-defined properties. The key components of the VFL are theoretical and computational nanoscience research; our user community and alliances with other research groups both within and outside Argonne; software development and mo deling capabilities; and high-performance computing resources.

Research Activities

• Nanocatalysis: Electronic structure calculations are used to elucidate the mechanisms underlying the catalysis of chemical reactions by nanoclusters.
• Computational nanophotonics: Rigorous electrodynamics calculations, often using the finite-difference time-domain, are undertaken to understand, for example, how complex metallic nanostructures such as metal films with periodic arrays of holes or nanowells, can lead to enhanced spectroscopic responses of relevance to chemical imaging and sensing.
• Quantum dynamics in nanoconfined environments: Wave packet calculations of the movement, spectroscopy and reactivity of molecules in nanoconfined environments such as fullerenes and carbon nanotubes are carried out.
• Methods and software development: We carry out work on parallelization of density functional theory codes such as G-PAW, as well as other programs such as our quantum and electrodynamics codes. We also work on the development of methods, particularly those that allow us to address the multiscale features of many nanoscience problems.