In developing new energy technologies, visualization tools for materials research can provide new insight into a wide range of phenomena. At Argonne National Laboratory, we have developed domain-specific visualization and analysis tools to augment the abilities of existing software. In contrast to existing tools operating on atomic geometry or derived surface meshes, our tools allow for analysis and rendering of volumetric phenomena, providing more expressive representation of material interfaces, and understanding of derived quantities. Since surface science is often inexact at atomic and sub-atomic scales, volumetric methods can more flexibly describe boundaries, express uncertainty, and correlate computational results with ground truth from microscopy sources.
Nanobowls
Bin Liu, Maria K.Y. Chan and Jeffrey Greeley at the Center for Nanoscale Materials (CNM) at Argonne are interested in using novel amorphous aluminum oxide (Al2O3) nanostructures, “nanobowls”, as multipurpose catalyst supports. The stability of synthesized nanostructures under reaction conditions is a key for the applications. The diffusion process is modeled on nanobowls consisting of 10,000 – 20,000 atoms using DL POLY, a molecular dynamics (MD) code. The MD simulations of pre-equilibrated system were conducted at temperatures in the range of 1000 – 1500K.
CO Adsorption in Catalysis
Aslihan Sumer and Julius Jellinek at Chemical Sciences and Engineering (CSE) are examining the bonding energetics of CO adsorption, using density functional theory (DFT) simulation in the NWChem package. The output of this simulation is a volumetric charge density field corresponding to orbitals of electrons in the molecule. The goal of this effort is to understand why carbon monoxide acts as a poisoning agent on certain catalysts (namely Platinum, as in this example), but not on others.
Amorphous Carbon Supersoot
Under the Center for Electrical Energy Storage EFRC, Vilas Pol at Argonne National Laboratory Materials Science Division (MSD) is experimenting with amorphous carbon structures usable as anode material in battery technology. These carbon structures are byproducts of combustion of plastics and similar organic compounds. Appearing as ordinary soot to the human eye, they in fact consist of diamond cores surrounded by sheaths of graphite. The graphite layers excel at trapping Lithium ion electrolyte, resulting in an effective battery from recycling processes. Alongside experimental synthesis, Kah Chun Lau and Larry Curtiss at MSD perform molecular dynamics simulation in LAMMPS, with the goal of understanding which processes result in optimal electrolyte storage material. MD supersoot simulations generate moderately large geometry (800,000 atoms), which is cumbersome to visualize as a ball-and-stick model.