High-throughput Structural Inferencing James P. Lewis, West Virginia University Research Corporation, DMR 0903225

1. High-throughput Structural InferencingJames P. Lewis, West Virginia University Research Corporation, DMR 0903225 Complex zeolites composed of Al, P, Si and O, i.e.“SAPO” are important molecular sieve materials for gas separation, catalysis, and ion exchange applications. Here, we show results of a fully automated HT simulation involving 1000 structures each with ab initio relaxation. Results (calculated literally overnight) are shown of a study for SAPO-34 zeolite material where six randomly placed Si (either at Al or P site) are distributed in a unit cell of 288 atoms and the resulting cohesive energy for each optimized structure is plotted versus the clustering factor (a quantity determining Si spatial correlation). We find that Si prefers conformations of pairs and triplets (as shown). Such HT simulations are broadly applied to any materials-doping scenario.

2. Engineering the Band Gap in a-SiJames P. Lewis, West Virginia University Research Corporation, DMR 0903225 Here we explore the structural consequences of electronic optimization in amorphous Si. By optimizing the electronic gap, we obtained significantly increased tetrahedral structural order in a-Si. A local energy gap exceeding 1.2 eV was targeted; the density functional code SIESTA was used for the calculations. Top left: initial, optimized DOS; Top right: evolution of gap with accepted Monte Carlo moves; Bottom: bond-angle distribution before and after optimization. A 64-atom cell was used. Coupled with automated HT simulation approaches (as discussed on the previous slide), these optimization techniques can be used to drive combinatorial materials design for many systems.

3. Broader ImpactsJames P. Lewis, West Virginia University Research Corporation, DMR 0903225 FIREBALL Review Article. Physica Status Solidi selected review paper on FIREBALL as the issue Highlight. Our method provides an extended treatment of the local-orbital and exchange-correlation theory. In our review, we discuss applications and future prospects of this code. This paper was highlighted by McNellis in Materials Views online. Student Impact: Kylee Underwood (female, graduate student at WVU, WV resident) and Cecil O’Dell (first- generation, undergraduate student at WVU, WV resident) Summer Institutes at WVU (Summer 2012) - will increase awareness of computational capabilities to faculty and students at PUIs and will cross-train experimentalists.