Learn More
NWChem is the software package for computational chemistry on massively parallel computing systems developed by the High Performance Computational Chemistry Group for the Environmental Molecular Sciences Laboratory. The software provides a variety of modules for quantum mechanical and classical mechanical simulation. This article describes the design and(More)
Several parallel algorithms for Fock matrix construction are described. The algorithms calculate only the unique integrals, distribute the Fock and density matrices over the processors of a massively parallel computer, use blocking techniques to construct the distributed data structures, and use clustering techniques on each processor to maximize data(More)
Recent developments in I/O systems on scalable parallel computers have sparked renewed interest in out-of-core methods for computational chemistry. These methods can improve execution time significantly relative to " direct " methods, which perform many redundant computations. However, the widespread use of such out-of-core methods requires efficient and(More)
We describe a generic programming model to design collective communications on SMP clusters. The programming model utilizes shared memory for collective communications and overlapping inter-node/intra-node communications, both of which are normally platform specific approaches. Several collective communications are designed based on this model and tested on(More)
On SMP clusters, mixed mode collective MPI communications , which use shared memory communications within SMP nodes and point-to-point communications between SMP nodes, are more efficient than conventional implementations. In a previous study, we proposed several new methods that made mixed mode collective communications significantly faster than the pure(More)