Title: Crystal structure determination by global optimisation in configuration space: a case study for distributed computing on the NRW-grid

Authors: G. Roth, C. Bischof, Th. Eifert

Addresses: Institute for Crystallography, RWTH Aachen University, Templergraben 55, 52062 Aachen, Germany. ' Institute for Scientific Computing, RWTH Aachen University, Templergraben 55, 52062 Aachen, Germany; Center for Computing and Communication, RWTH Aachen University, Templergraben 55, 52062 Aachen, Germany. ' Center for Computing and Communication, RWTH Aachen University, Templergraben 55, 52062 Aachen, Germany

Abstract: The problem of ab-initio crystal structure determination from (incomplete) powder X-ray diffraction data is formulated as a global optimisation problem. The problem is of complexity class P, which suggests that the problem itself is practically infeasible for any but trivial structures. Yet, we show in this report that the inherent symmetry of the problem along with suitable heuristics and with massive computational power, allows the determination of structures with up to 20 atoms in the asymmetric unit from scratch. We give an overview of the methods employed and show numerical examples obtained by solving a model problem on the NRW-grid, which harnesses the computational power of several hundred computers at several universities in the state of Northrhine-Westfalia.

Keywords: crystal structure determination; global optimisation; distributed computing; grid computing; Condor; crystal structures; incomplete data; powder X-ray diffraction; modelling.

DOI: 10.1504/IJCSE.2011.042020

International Journal of Computational Science and Engineering, 2011 Vol.6 No.3, pp.168 - 174

Available online: 20 Aug 2011 *

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