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Supercomputing Awards Support Exploration of Surface Chemistry, Accelerator Technology

(Photo - the Intrepid supercomputer)
Intrepid, the IBM supercomputer at ANL. (Photo courtesy Argonne Leadership Computing Facility.)

Not one, but two SLAC groups look to benefit from their share of 1.7 billion hours of computing time awarded to researchers by the Department of Energy's Office of Advanced Science Computing Research. The awards, announced November 30 by Secretary of Energy Steven Chu, are presented as part of the DOE's Innovative and Novel Computational Impact on Theory and Experiment program, or INCITE. They provide time on two of the most powerful supercomputers in the world—Intrepid, an IBM Blue Gene/P machine at Argonne National Laboratory, and Jaguar, a Cray XT5 machine at Oak Ridge National Laboratory.

"The INCITE award is fantastic," said Frank Abild-Pedersen, a SLAC staff scientist in SUNCAT, the Center for Sustainable Energy through Catalysis, part of a collaboration awarded 15,000,000 processor hours on the IBM supercomputer. According to Abild-Pedersen, time on a supercomputer is vital to SUNCAT's efforts to understand the workings of catalysts, substances that can affect chemical reactions without themselves being affected. Catalysts are already widely used in industry, and improved catalysts hold the key to more efficient fuel cells, better rechargeable batteries—possibly even artificial photosynthesis.

(Photo - Jaguar 6.0)
Jaguar, the Cray supercomputer at ORNL. (Photo courtesy National Center for Computational Sciences.)

Abild-Pedersen said researchers at SUNCAT can use theory to model the workings of catalysts—to a point. At sizes below a few nanometers, or billionths of a meter, the properties of catalytic systems do not behave according to the rules that govern other size scales, which means that very detailed, data-intensive simulations are required to double-check the theorists' calculations at these nanoscales. But the only computers capable of such simulations are supercomputers.

"And we need those calculations to justify what we're doing," Abild-Pedersen said—to confirm that the SUNCAT group is on the right track.

The second project benefitting from supercomputer time is FACET, the Facility for Advanced Accelerator Experimental Tests. According to Mark Hogan, head of the plasma acceleration group in SLAC's Advanced Accelerator Research Department, long-time collaborator Warren Mori of UCLA and his group will use their 12,000,000 processor hours on the Cray supercomputer to test advanced plasma accelerator concepts, the focus of FACET, with the latest simulation codes.

"That's been their job from the get-go," Hogan said. The UCLA group has collaborated with SLAC since 1998, when plasma wakefield experiments began at the lab. The difference now is in the complexity of the simulations. Instead of simulating electrons being accelerated in individual plasma cells, Mori's group will focus on "simulating the very extreme conditions in an entire plasma accelerator," in the virtual world of simulation space, Hogan said. This is a computationally difficult feat, due to the need to include both the tiny distance scales of electron beams and the large distance scales of the combined plasma cells.

According to Hogan, these codes are an "essential element" for designing future plasma accelerators.

—by Lori Ann White
SLAC Today, December 14, 2010