The addition of electron donors to the vacant A site of defect-perovskite structure tungsten trioxide causes a series of structural and chemical phase transitions; for instance, in the well-known case of the sodium tungsten bronzes (NaxWO3). Here we calculate the effect of the addition of electronic charge to WO3 without the complication of also including sodium ions. Our density functional theory method enables isolation of electronic effects from the additional size, chemical, and disorder effects present in experimental samples. Our calculated low-temperature phase diagram between x=0 and x=1 moves from the initial low-temperature monoclinic phase through a second (centered) monoclinic phase, an orthorhombic phase, a tetragonal antiferroelectric, and an aristotypic cubic phase, in broad agreement with the experimentally-observed transformations in NaxWO3. Our work confirms that the observed structural transformations are driven primarily by electronic factors. We find that the dominant electronic effect is the covalent interaction between the tungsten 5d and oxygen 2p orbitals.

SUMMARY Grid‐based simulation usually involves large quantities of data at each stage of the simulation process. These data include simulation input and output files, intermediate results files, log and error files, associated metadata, and information capturing the processes that generate the data. The question of how to effectively store and manage data files within a Grid computing environment is increasingly becoming an important issue. This paper illustrates how we built a lightweight e‐Science infrastructure for data management within a Grid computing environment, including the integration of data curation activities into the entire Grid‐based simulation process. Rather than focusing on specific implementation details, we aim to identify the key issues and research challenges, describing how various existing technologies and tools can be best integrated to address these requirements and challenges. Although the case of quantum mechanical simulation of materials properties is used in the paper, much of the discussion is as generic as possible so that approaches, methods and practice (e.g. integrated approach, workflow taxonomy and development approach, simple but useful semantic annotation approach) can be applied to wider domains and disciplines to facilitat the digital research. A comparison between our approach and Cloud computing, and lessons learned in data management within the Grid computing environment, are also presented. Copyright © 2012 John Wiley & Sons, Ltd.

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