Palladium is an ideal model system for understanding metal-hydrogen interactions, as it catalyzes the H₂ to 2H reaction on its surface at room temperature, which allows for simple control of hydrogen concentration in Pd. Hydrogen has a high mobility and acts like a nearly random lattice gas occupying octahedral sites in FCC Pd. The change in local site energy due to stress centers, like edge dislocation cores, leads to the formation of Cottrell atmospheres. These changes in the hydrogen local environment can be measured using inelastic neutron scattering, and predicted using DFT calculations of the hydrogen potential energy in Pd.

1. “First-principles calculation of H vibrational excitations at a dislocation core of Pd”
   H. M. Lawler and D. R. Trinkle. in review (2010): preprint

This work in collaboration with Brent Heuser at UIUC and is funded by the NSF DMR program. Computational resources are provided through the NSF TeraGrid program.