One of the major challenges of modern quantum chemistry (QC) is to apply it to large systems with thousands of correlated electrons and basis functions. The availability of supercomputers and development of novel methods are critical to realize this challenge. In particular, we employ linear scaling Fragment Molecular Orbital (FMO) method which decompose the large system into smaller, localized fragments which can be treated with high-level QC method like MP2. FMO is inherently scalable since the individual fragment calculations can be carried out simultaneously on separate processor groups. It is implemented in GAMESS, a popular ab-initio QC program. We present the scalability and performance of FMO on Intrepid (Blue Gene/P) and Blue Gene/Q systems at Argonne Leadership Computing Facility. We also describe our work on multithreading the integral kernels in GAMESS to effectively use the enormous number of cores and threads of new generation supercomputers. Lastly, we will present several benchmark results, including FMO2-MP2 calculations on water clusters.

Toward large-scale fully ab initio calculations using fragment molecular orbital method on petascale computers

245th National Meeting (2013)

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