Structure code

Zeolite IZA structure code Typical unit cell composition Si02/Al203 range by synthesis Dimensionality of channel system Pore apertures (nm)... 

Two aspects of tlie Morgan Algorithm play a dominant role for structure coding ... 

As this short example shows. PDB files use different syntax for different records and both writing and reading such files require much effort. Another problem is the extensibility of this format to handle new kinds of information, which further complicates the file structure. The Protein Data Bank has been faced with the consequences - the existing legacy data comply with several different PDB formats, so they are not uniform and they arc more difEcuh to handle (145, 155, 157]. As mentioned in Section 2,9.7.1, there is a much more flexible and general way of representing molecular structure codes and associated information - the STAR file format and the file formats based on it. 

The data analysis module of ELECTRAS is twofold. One part was designed for general statistical data analysis of numerical data. The second part offers a module For analyzing chemical data. The difference between the two modules is that the module for mere statistics applies the stati.stical methods or rieural networks directly to the input data while the module for chemical data analysis also contains methods for the calculation ol descriptors for chemical structures (cl. Chapter 8) Descriptors, and thus structure codes, are calculated for the input structures and then the statistical methods and neural networks can be applied to the codes. 

The structure coding depends strongly on the properties which arc to be modeled. For an explanation of the different structure codes and their applications. sec Chapter 8,... 

The band-structure code, called BAND, also uses STO basis sets with STO fit functions or numerical atomic orbitals. Periodicity can be included in one, two, or three dimensions. No geometry optimization is available for band-structure calculations. The wave function can be decomposed into Mulliken, DOS, PDOS, and COOP plots. Form factors and charge analysis may also be generated. 

ChemlDplus at the National Library of Medieine is a database of 56,645 chemical structures. Code of Federal Regulations. 

One of the earliest direct bonuses of imaging zeolitic catalysts by HRTEM was the discovery (10) that the nominally phase-pure ZSM-5 (structure code MFI) contained sub-unit-cell coherent intergrowths of ZSM-11 (MEL). It soon became apparent (46) that, depending on the mode of synthesis of these and other pentasil (zeolitic) catalysts, some specimens of ZSM-5 contained recurrent (regular) intergrowths of ZSM-11. It also emerged that intergrowths of offretite and erionite are features of both nominally phase-pure erionite and of pure offretite and of many members of the so-called ABC-6 family of zeolites (47). 

The 12-MR pores in the CIT-1 structure [International Zeolite Association (IZA) structure code, CON] are 6.8 x 6.4 A in diameter while the intersecting 10-MR pores are5.1x5.lA.B oth pore dimensions might be regarded as small for the ring size but interestingly molecular simulation of the pores between 0 and 200 K indicate the 10-MR pores can flex by >1 A (25). The potential catalytic activity of... 

ITQ-4, which has the formula Si32064.(C 4I I20NF)216, is another relatively new 12-MR ID channel-type zeolite that forms a pure silica polymorph (50-52). The structure of ITQ-4, which has been assigned the structure code IFR, is shown in Fig. 8. This view along the 001 direction reveals the distorted 12-MR pores that are... 

The structure of SSZ-35 (IZA structure code STF) as viewed in the [001] direction is shown in Fig. 17. The dimensions of the 10-MR structures are 5.5 x 6.1 A and the diameter of the 18-MR structures is 12.5 x 9 A. This pore structure is in contrast to the structure of SSZ-44 (IZA structure code SFF) shown in Fig. 18, where the 10-MR structures are nearly spherical (5.8 A) and the 18-MR structures are slightly larger (12.9 x 9 A). These small differences in pore size apparently translate into startling differences in reactivity. A study of m-xylene conversion shows a high degree of isomerization versus disproportionation, which is consistent with a 10-MR pore system (47). The interesting data is the para to ortho selectivity in the isomerization products, where SSZ-44 exhibited a higher para/ortho... 

The structure of Cloverite (IZA structure code, CLO) has limited thermal stability in air, which is not surprising for gallophosphates. It has been shown that Cloverite is stable in ambient air or a vacuum up to 500°C, but if the molecular sieve is cooled below 100°C, the structure collapses (153). If the calcined Cloverite is immediately placed in hydrocarbon solvents it can be stored at RT for several months. 

The calculation of Mayer bond orders and valence indices is straightforward using the codes that Mayer has made available on the Internet [14]. The formulas have been built into several electronic structure codes, like HONDO [15], Gaussian 03 [16] (note that in Gaussian only the closed-shell formulas have been coded), ADF [17], and some versions of GAMESS [18]. 

Structure Code (other names) Nx/u.c. Channels Applications... 

In Tables -A, we report oscillator strengths for some fine structure transitions in neutral fluorine, chlorine, bromine and iodine, respectively. Two sets of RQDO/-values are shown, those computed with the standard dipole length operator g(r) = r, and those where core-valence correlation has been explicitly introduced, Eq. (10). As comparative data, we have included in the tables /-values taken from critical compilations [15,18], results of length and velocity /-values by Ojha and Hibbert [17], who used large configuration expansions in the atomic structure code CIVS, and absolute transition probabilities measured through a gas-driven shock tube by Bengtson et al. converted... 

The RQDO /-values conform with the recommended values by Wiese et al. [18] for the 3p ( P) 4s-3p ( P) 4p transitions in C//better than those of the much more complex theoretical procedure of Ojha and Hibbert [17], who used large multiconfiguration expansions in the atomic structure code CIVS. On the other hand, the discrepancies between the length and velocity CIVS oscillator strengths are not negligible. Wiese et al. [18] remark that, for the case of the 4s " P-4p multiplet, the stronger lines measured by Bengtson et al. [16] seem to be affected by self-absorption (Table 2). 

Another POLIDCASYR extension ensures that structural features of the backbone can be distinguished from those occurring in side chains. The system furthermore augments structure codes for polymers using a controlled vocabulary of keywords, such as epoxy resin , aminoplast or phenoplast . 

A more detciiled account of the parallelization may be of interest to researchers seeking to parallelize electronic structure codes. We consider therefore in this section those aspects of the parallelization that are not directly related to the direct Cl algorithm discussed in Section 2. We first state our overall implementationaJ objectives, followed by some more practical details, including also a description of the PVM [17,18] message passing facility used. 

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