Root atom

Determine root atom atom type bond type torsion angle by random number ... 

The first three searches compared the performance of different similarity measures with the full INBS frequency data. When the performance of the frequency Tanimoto measure and the city block metric was compared, it was found that the hits ranked to the top using the Tanimoto measure were not as similar to the query structure as those ranked top by the city block metric. Generally it was found that the city block and Euchdean distance measures ranked the hits equally well, however in two cases the city block ranking was better than the Euclidean ranking, so use of the city block metric may be preferred. The fourth search used only the paths from the most connected atom in the structure in a city block metric calculation. A comparison of the performance of the INBS search for individual query structures using the city block metric for all paths and for the Morgan root atom alone is discussed below. 

Some of the top structures however, had extra side chains, or had side chains which were longer or shorter than those in the query. Searches based on the canonical root atom did not produce good results. Although the three existing occurrences of the query structure were ranked in the top five structures, the other structures ranked similar to the query were in fact much more complex, with much larger patterns and numbers of atoms. 

Friction can now be probed at the atomic scale by means of atomic force microscopy (AFM) (see Section VIII-2) and the surface forces apparatus (see Section VI-4) these approaches are leading to new interpretations of friction [1,1 a,lb]. The subject of friction and its related aspects are known as tribology, the study of surfaces in relative motion, from the Greek root tribos meaning mbbing. 

The potential fiinctions for the mteractions between pairs of rare-gas atoms are known to a high degree of accuracy [125]. Flowever, many of them use ad hoc fiinctional fonns parametrized to give the best possible fit to a wide range of experimental data. They will not be considered because it is more instmctive to consider representations that are more finnly rooted in theory and could be used for a wide range of interactions with confidence. 

It is remarkable that tire roots of the SFA go back to the early 1960s [1], Tabor and Winterton [2] and Israelachvili and Tabor [3] developed it to the current state of the art some 15 years before the invention of the more widely used atomic force microscope (AFM) (see chapter B1.19). 

Thus, if we knew the second moment of the local density of states we should be able to determine the atomic binding energy via the square root relationship. However, as quantum... 

P(r,i) is the pairwise potential, which, depending upon the model, can be considered tc include electrostatic and repulsive contributions. The second term is a function of th< electron density, and varies with the square root, in keeping with the second-momen approximation. The electron density for an afom includes contributions from the neigh bouring atoms as follows ... 

L has only diagonal entries, the matrix L is identical to its transpose L = L. The atomic Drdinates are thus obtained by multiplying the square roots of the eigenvalues by the jenvectors. 

A molecular fitting algorithm requires a numerical measure of the difference between two structures when they are positioned in space. The objective of the fitting procedure is to find the relative orientations of the molecules in which this function is minimised. The most common measure of the fit between two structures is the root mean square distance between pairs of atoms, or RMSD ... 

Other Polyatomic Anions. Names for other polyatomic anions consist of the root name of the central atom with the ending -ate and followed by the valence of the central atom expressed by its oxidation number. Atoms and groups attached to the central atom are treated as ligands in a complex. 

Exceptions to the use of the root name of the central atom are antimonate, bismuthate, carbonate, cobaltate, nickelate (or niccolate), nitrate, phosphate, tungstate (or wolframate), and zincate. 

Yohimbine (104), also from the bark of C.johimbe K Schum. and from the roots of R. serpentina (1. ) Benth. has a folk history (unsubstantiated) of use as an aphrodisiac. Its use has been confirmed experimentally as a local anesthetic, with occasional employment for rehef ia angiaa pectoris and arteriosclerosis, but is frequently contraindicated by its undesired renal effects. Yohimbine and some of its derivatives have been reported as hahuciaogenic (70). In addition, its pattern of pharmacological activities ia a variety of animal models is so broad that its general use is avoided. All ten carbon atoms of secologanin (102) as well as the entire skeleton of tryptamine (98, R = H) are clearly seen as iatact portions of this alkaloid. 

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