PSC Soliciting Bold X-PLORers

Nick Nystrom, scientific specialist

The PSC is seeking collaborators for early testing of a newly parallelized version of X-PLOR on the Cray T3E. Developed by Axel Brünger and his group at Yale, X-PLOR is a state-of-the-art program for determining three-dimensional structures of proteins and other macromolecules using X-ray crystallographic and/or nuclear magnetic resonance (NMR) data.

Nick Nystrom (PSC) along with Rich Graham and Bin Chen (CRI) recently undertook the task of parallelizing the calculation of structure factors and their derivatives for normal as well as anomalous scatterers. This effort complements earlier work by Paul Adams, a postdoc in Brunger's group, who adapted the molecular dynamics portion of X-PLOR for execution on parallel and distributed systems. Calculation of structure factors dominates the time required for structure refinement, and its parallelization enables computations which would otherwise be intractable due to memory constraints and also reduces the time to solution. Refinement calculations on grids of dimensions up to 486x240x352 have been successfully carried out on the Cray T3D, for which preliminary scalability data is encouraging.

PSC is now soliciting as collaborators X-PLOR users with large computational demands who would benefit from having early access to a very fast, distributed memory version of X-PLOR on the Cray T3E. This project is still in the development stage; therefore, a "friendly user" allocation will be awarded to qualified applicants in exchange for working with PSC to ensure that the parallel version of X-PLOR is well-optimized for problems of interest to leading-edge researchers. For additional information, please contact Nick Nystrom at nystrom@psc.edu.