ICDD'S New PDF-4 Organic Database: Search Indexes, Full Pattern Analysis and Data Mining

Abstract

In an attempt to fill a gap between fully automatic search/match programs and purely manual methods based on paper products, a relational database plug-in has been developed that functions as a PC-based Search/Index program for extracting information from PDF-4 powder diffraction databases. The plug-in provides an adjustable search window and match window to account for experimental errors. Both Hanawalt (Hanawalt, J.D. and Rinn, H.W. (1936). Ind. Eng. Chem. Anal., 8, 244.; Hanawalt, J.D. (1976). Advances in X-Ray Analysis, 20, 63–73; Hanawalt, J.D. (1983). Crystalograplty in North America, Apparatus and Methods, Ch. 2, pp. 215–219. American Crystallographic Association.] and Fink [Bigelow, W. and Smith, J.V. (1965). ASTM Spec. Tech. Puhl. STP, 372, 54–89.] search methods are incorporated. In this article, we report search-indexing results obtained with the new PDF-4 plug-in applied to a new relational database, the PDF-4/Organics 2003. This database has 24 385 experimental entries and 122816 calculated patterns derived from the Cambridge Crystallographic Database (CSD). We introduce a goodness of match (GOM) parameter to describe the relative agreement between the experimental input data and selected reference patterns from the PDF-4/Organics 2003. The relevance of the GOM is illustrated in several example problems. Multiphase samples can be treated on a phase-by-phase basis.