Hydrogen Bond Energetics:  A Simulation and Statistical Analysis ofN-Methyl Acetamide (NMA), Water, and Human Lysozyme†

2001 ◽  
Vol 105 (44) ◽  
pp. 11000-11015 ◽  
Author(s):  
Matthias Buck ◽  
Martin Karplus
Keyword(s):  
Hydrogen Bond ◽  
Statistical Analysis ◽  
Human Lysozyme

Hydrogen Bonding to Thiocyanate Anions: Statistical and Quantum-Chemical Analyses

1998 ◽  
Vol 54 (3) ◽  
pp. 316-319 ◽  
Author(s):  
J. P. M. Lommerse ◽  
J. C. Cole
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Statistical Analysis ◽  
Lone Pair ◽  
Unexpected Result ◽  
Acta Cryst ◽  
Energy Calculations ◽  
Acceptor Atom ◽  
Detailed Statistical Analysis ◽  
Nitrogen Lone Pair

A statistical analysis of entries from the CSD (Cambridge Structural Database) showed that the average hydrogen-bond geometry to the nitrogen acceptor atom of the thiocyanate anion was not collinear with respect to the molecular axis of the anion and so not collinear with the nitrogen lone pair [Tchertanov & Pascard (1996). Acta Cryst. B52, 685–690]. This somewhat unexpected result has been investigated further using theoretical energy calculations applying Intermolecular Perturbation Theory in combination with a more detailed statistical analysis of an appropriate CSD dataset. The energy calculations pointed to the formation of the strongest hydrogen bonds in the nitrogen lone-pair direction. The statistical analysis showed that this directionality occurs in cases where the N atom accepts one hydrogen bond only. The non-linear average hydrogen-bond geometry observed in the earlier study can be attributed to multiple hydrogen bonding to the N atom. In such cases, there is a shift away from the optimum orientation.

Oxime–Carboxyl Hydrogen Bonds: the Preferred Interaction Determining Crystal Packing of `Carboxyoximes'

1998 ◽  
Vol 54 (6) ◽  
pp. 866-871 ◽  
Author(s):  
J. K. Maurin
Keyword(s):  
Hydrogen Bond ◽  
Statistical Analysis ◽  
Hydrogen Bonds ◽  
Ab Initio ◽  
Carboxylic Acids ◽  
Quantum Chemical Calculations ◽  
Pyruvic Acid ◽  
Quantum Chemical ◽  
Crystal Packing ◽  
Hydrogen Bond Interactions

The statistical analysis of hydrogen-bond interactions formed by oximes and carboxylic acids has been performed. Ab initio quantum-chemical calculations have been used to rationalize the observed preference for the oxime–carboxyl interaction compared with homologous binding (carboxyl–carboxyl and oxime–oxime). The crystal packing observed in the structure of pyruvic acid oxime (hydroxyiminopyruvic acid) has been explained as the consequence of a combination of the energetically optimal structure of the isolated molecule and the optimal interaction of monomers forming a dimer.

scholarly journals New software for statistical analysis of Cambridge Structural Database data

2011 ◽  
Vol 44 (4) ◽  
pp. 882-886 ◽  
Author(s):  
Richard A. Sykes ◽  
Patrick McCabe ◽  
Frank H. Allen ◽  
Gary M. Battle ◽  
Ian J. Bruno ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Statistical Analysis ◽  
Cone Angle ◽  
Three Dimensional ◽  
Cambridge Structural Database ◽  
Data Analyses ◽  
Angle Correction ◽  
Other Information ◽  
Structural Database ◽  
Components Analysis

A collection of new software tools is presented for the analysis of geometrical, chemical and crystallographic data from the Cambridge Structural Database (CSD). This software supersedes the programVista. The new functionality is integrated into the programMercuryin order to provide statistical, charting and plotting options alongside three-dimensional structural visualization and analysis. The integration also permits immediate access to other information about specific CSD entries through theMercuryframework, a common requirement in CSD data analyses. In addition, the new software includes a range of more advanced features focused towards structural analysis such as principal components analysis, cone-angle correction in hydrogen-bond analyses and the ability to deal with topological symmetry that may be exhibited in molecular search fragments.

Statistical analysis of noncovalent interactions of anion groups in crystal structures. II. Hydrogen bonding of thiocyanate anions

1996 ◽  
Vol 52 (4) ◽  
pp. 685-690 ◽  
Author(s):  
L. Tchertanov ◽  
C. Pascard
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Statistical Analysis ◽  
Crystal Structures ◽  
Solid Angle ◽  
Noncovalent Interactions ◽  
Spherical Cap ◽  
Hydrogen Bond Acceptor ◽  
Thiocyanate Anion ◽  
Multiple Hydrogen Bonding

The hydrogen-bond acceptor function of the thiocyanate anion is analyzed in 52 crystal structures retrieved from the Cambridge Crystallographic Database. All modes of hydrogen-bond coordination are represented: by the sulfur, by the nitrogen and by the π-system of the anion. The preferred areas for the H donors (D = OH and NH groups) were determined: (a) around sulfur, as a torus centered at the S end, the axis of which is the linear anion, and with an average DSON angle of 99°, and (b) around nitrogen, on a spherical cap delimited by the solid angle, SOND (average = 145°), with the linear anion. The anion-acceptor function is characterized by multiple hydrogen bonding and, in most cases (80%), thiocyanate binds through both acceptor centers (S and N). Important backbonding of sulfur in the thiocyanate anion is structurally evidenced.

scholarly journals Contribution of a Hydrogen Bond to the Thermal Stability of the Mutant Human Lysozyme C77/95S.

1994 ◽  
Vol 17 (5) ◽  
pp. 612-616
Author(s):  
Hirofumi YAMADA ◽  
Eiko KANAYA ◽  
Yoshio UENO ◽  
Morio IKEHARA ◽  
Haruki NAKAMURA ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bond ◽  
Human Lysozyme ◽  
Thermal Stability Of

Statistical analysis of classification

1966 ◽  
Vol 24 ◽  
pp. 188-189
Author(s):  
T. J. Deeming
Keyword(s):  
Multivariate Analysis ◽  
Statistical Analysis ◽  
Classification Scheme ◽  
Analytical Procedure ◽  
Narrow Band ◽  
Scientific Research ◽  
Maximum Amount ◽  
Amount Of Information

If we make a set of measurements, such as narrow-band or multicolour photo-electric measurements, which are designed to improve a scheme of classification, and in particular if they are designed to extend the number of dimensions of classification, i.e. the number of classification parameters, then some important problems of analytical procedure arise. First, it is important not to reproduce the errors of the classification scheme which we are trying to improve. Second, when trying to extend the number of dimensions of classification we have little or nothing with which to test the validity of the new parameters.Problems similar to these have occurred in other areas of scientific research (notably psychology and education) and the branch of Statistics called Multivariate Analysis has been developed to deal with them. The techniques of this subject are largely unknown to astronomers, but, if carefully applied, they should at the very least ensure that the astronomer gets the maximum amount of information out of his data and does not waste his time looking for information which is not there. More optimistically, these techniques are potentially capable of indicating the number of classification parameters necessary and giving specific formulas for computing them, as well as pinpointing those particular measurements which are most crucial for determining the classification parameters.

Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1202-1203
Author(s):  
Gianluigi Botton ◽  
Gilles L'espérance
Keyword(s):  
Statistical Analysis ◽  
Spatial Resolution ◽  
Personal Computer ◽  
Systematic Study ◽  
Present Author ◽  
Chemical Elements ◽  
Detection Limits ◽  
Research Groups ◽  
Quantitative Performance ◽  
Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

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