Structures Graphics Display

SemiChem products are available at http //www.semichem.com. AMPAC , available as a stand-alone product with Windows-based and workstation level interfaces, is a semiempirical quantum mechanical program featuring SAMI, AMI, MNDO, MNDO/d, PM3, MNDO/C, MINDO/3 semiempirical methods. AMPAC also includes a graphical user interface (GUI) that builds molecules and offers full visualization of results. The SYBYL/Base program offered by Tripos, Inc. (products described below) provides an interface with interactive graphing and structural display tools that can be used to access AMPAC s calculation tools. 

For single-crystal diffraction, a good-quality single crystal of the sample of interest is required. From the angles and intensities of diffracted radiation, the structure of the crystal can be elucidated and the positions of the molecules in the unit cell can be determined. The result is often displayed graphically as the asymmetric unit, which is the smallest part of a crystal structure from which the complete structure can be obtained using space-group symmetry operations. 

Tel. 212-460-1622, e-mail griepke spint.compuserve.com Structure building. Stick and dot surface display. Geometry optimization dynamics by AMBER parameters. MNDO and AMI semiempirical calculations. AUTONOM for computerized assignment of chemical nomenclature to structures from graphical input. Beilstein and Brookhaven chemical databases in CD-ROM format. PC. 

With the graphical output program in place, it was possible to provide our scientists with the first fruits of the early SOCRATES system graphical structure display at a terminal of compounds from the company files (generated fi om the stored WLN s via connection tables). The next step was to provide a structure match capability. As mentioned earlier, within INDABS there already existed a fast chemical novelty search which employed an index of topological codes. This was easily integrated into SOCRATES to accept graphically drawn structures fi om SENTRY instead of WLN s. 

We consider that UML is a useful notation for displaying graphically the structure of a system and the relationships between the system, its components and its users. However, UML is not a substitute for a precise formal specification. Although UML has a formal sub-language called Object Constraint Language (OCL), it is rarely used, poorly supported by commercial tools and much less expressive than Perfect Developer notation. 

The same types of graphic analysis for any choice of the matrix V are used. Here an example of the graphic analysis based on an industrial on-line data is presented. The figures illustrate results of static linear PLS model, in which NIR data fix>m an oil refinery is used to model density of the product The vectors in the algorithm are displayed graphically to illustrate the structure and variation in data. The basic plots are 1. ta versus it, The vectors (t,) decompose the data matrix X. Therefore the plots of t, versus tb show us the sample (time) variation in data. Fig 1 reveals that the process (samples) is changing with the time. Arrows in Fig 1 visualise the drift on 1.-4. PLS components. The dynamic behaviour can be clearly seen even on the first two score vectors. Therefore, it cannot be expected that the same model will be valid at the... 

Using 200 specific queries, each of which is known to retrieve at least its parent, the mean number of database structures retrieved is five 88 queries retrieve only the parent structures, while the maximum number of database structures retrieved is only 36. Using the smaller set of 60 structurally explicit generic queries, the mean number of database structures retrieved is 13 16 of these queries retrieve only their parent structures, while the worst case query retrieves 135 structures. These results are displayed graphically in Figures 6 and 7. 

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