Structure Distribution File

The Structure Distribution File format is another means for representing inorganic compounds on a computer system. With the Gmelin Database it is used as the intrinsic storage format for substance and structure information. The SDF format has been developed to store the same amount of information as is contained in a ROSDAL string, but there is no one-to-one correspondence between different constructs of the ROSDAL specification and of the SDF format. 

The structure distribution file consists of one or several header records, followed by a number of optional lists. The sequence of headers and lists is such that the multicomponent structure of a general inorganic substance can be represented the following scheme indicates the overall structure ... 

Structure Distribution File, File and Record Formats , Version 2.03, December 1991, Technical Documentadon, Beilstein Institute, Frankfurt/Main, 1991. 

CAS = Chemical Abstracts Service CT = connection table IDC = Internationale Dokumentationsgesellschaft fiir Chemie (International Documentation Society for Chemistry) 1ST = inorganic structure table ROSDAL = representation of structure description arranged linearly SDF = strucmre distribution file. 

Chemical Abstracts Service Registry Structure Standard Distribution File Chemical Abstracts Service Columbus, Ohio, 1977. 

Another recent database, still in evolution, is the Linus Pauling File (covering both metals and other inorganics) and, like the Cambridge Crystallographic Database, it has a "smart software part which allows derivative information, such as the statistical distribution of structures between symmetry types, to be obtained. Such uses are described in an article about the file (Villars et al. 1998). The Linus Pauling File incorporates other data besides crystal structures, such as melting temperature, and this feature allows numerous correlations to be displayed. 

In terms of nonlinear dynamical systems, the second waveguide of the junction can be considered as a system that is initially more or less far from its stable point. The global dynamics of the system is directly related to the spatial transfomation of the total field behind the plane of junction. In structure A, the initial linear mode transforms into a nonlinear mode of the waveguide with the same width and refractive index. In the structure B, the initial filed distribution corresponds to a nonlinear mode of the first waveguide it differs from nonlinear mode of the second waveguide, however. The dynamics in both cases is complicated and involves nonlinear modes as well as radiation. Global dynamics of a non-integrable system usually requires numerical simulations. For the junctions, the Cauchy problem also cannot be solved analytically. 

A second initiative is being developed by Dr. Ann Richard and coworkers at the EPA. The Distributed Structure-Searchable Toxicity (DSSTox) public database network is a flexible community-supported, web-based approach for the collation of data. It is based on the SDF format for the representation of chemical structure. It is intended to enable decentralized, free public access to toxicity data files. This should allow users from different disciplines to be linked. Public, commercial, industry, and academic groups have also been asked to contribute to, and expand, the DSSTox public database network. Data from potentially any toxicological endpoint can be collated in the DSSTox public database network, including both human health, and environmental endpoints (Richard et al 2002 Richard and Williams, 2002). 

Fig. 1.7. Distribution of the number of atoms in the small molecule organic and organometallic structures included in the Cambridge Crystallographic Data File in the years 1973 and 1982...

The proposed standard may be obtained using anonymous file transfer from titan.cs.rice.edu (in public/HPFF/draft). An effort commenced January 1994 to extend the HPF proposal to accommodate irregular data distributions and to support parallel 1/O and more complex data structures, as well as task-driven MIMD computation. Additional information is available by sending electronic mail to hpff-info cs.rice.edu. 

To account for the presumably statistical distribution of Ni and Sn atoms in the 2(c) and 3(g) sites in this crystal structure, the initial distribution of atoms in the unit cell has been assumed as listed in Table 7.2. The initial profile and structural parameters are found in the input file for LHPM-Rietica on the CD, the file name is Ch7Ex01a.inp. Experimental diffraction data, collected on a Rigaku TTRAX rotating anode powder diffractometer using Cu Ka radiation in a continuous scan mode, are located on the CD in the file Ch7Ex01 CuKa.dat. 

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