Dimer tilting is somewhat disordered due to the high temperature. The slab includes 232 silicon and 72 hydrogen atoms. Qiming Zhang, a materials scientist working at PSC as part of Cray Research's Parallel Applications Technology Program, translated Bernholc' QMD code to run on the T3D while also taking advantage of high speed communication between the T3D and C90. 6 Gflops using 128 T3D processors, compared to 2.3 Gflops on four C90 processors, one-fourth of the machine in both cases. Using the T3D code, Bernholc carried out a series of heating up experiments.
More recent simulations focus on diffusion across a heated surface.
Further improving on the C90 studies, these calculations allow the adatoms to follow any pathway available to them. So far, despite frequent oscillations in the tilting of the dimers at high temperatures, the jumps correspond to the zero temperature pathways. For the flat surface, the pathway is consistent with low temperature, exactly what we'd expect. We will do the same thing across the step edges. In this high temperature regime, we can see how the jumps occur in real time and probe for new and unforeseen diffusion mechanisms.