Seminar Details:

LANS Informal Seminar
"Algorithms and Software for Quantum Chemistry at Petascale and Beyond"

DATE: February 20, 2013

TIME: 15:00:00 - 16:00:00
SPEAKER: Jeff Hammond, Assistant Computational Scientist, ALCF
LOCATION: Building 240, 4301, Argonne National Laboratory

Quantum chemistry faces many challenges on petascale supercomputers due to a changing landscape of processing architecture and the enormous scale of these systems. Over the past 10 years, systems have grown in size by a factor of a thousand in some cases and within a node there is significantly more parallelism. This talk will start by considering the NWChem software package and it's coupled-cluster (CC) codes, which are scalable to 100,000 cores on Cray supercomputers and have rich scientific capability. From here, we consider three research projects to develop new coupled-cluster algorithms for modern supercomputers. The first of these is the development of CC for GPUs, where we observe approximately an order-of-magnitude speedup with respect to existing codes for CCSD at workstation scale. The second project is a complete redesign of tensor contraction algorithms using novel techniques from dense linear algebra. This completely eliminates load-imbalance and allows for topology-aware mapping on systems with torus interconnects (e.g. Blue Gene and "K"). Finally, we demonstrate how inspector-executor techniques can be used to eliminate dynamic task scheduling in NWChem CC codes, which can lead to a substantial reduction in time-to-solution.

This work has been done in collaboration with Eugene DePrince (Georgia Tech), Edgar Solomonik (Berkeley), Devin Matthews (Texas), David Ozog (Oregon), Pavan Balaji (Argonne) and Jim Dinan (Argonne).


Please send questions or suggestions to Jeffrey Larson: jmlarson at anl dot gov.