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  • Atomic, Molecular and Optical Physics  (32)
  • Reaction paths  (4)
  • Shape analysis  (4)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 58 (1981), S. 309-330 
    ISSN: 1432-2234
    Schlagwort(e): Catchment regions ; Potential energy surfaces ; Reaction paths ; Chemical structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The space of internal coordinates of a molecular system is partitioned into catchment regions of various critical points of the energy hypersurface. The partitioning is based on an ordering of steepest descent paths into equivalence classes. The properties of these catchment regions and their boundaries are analyzed and the concepts of chemical structure, reaction path and reaction mechanism are discussed within the framework of the Born-Oppenheimer and energy hypersurface approximations. Relations between catchment regions and the chemically important reactive domains of energy hypersurfaces, as well as models for “branching” of reaction mechanisms, caused by instability domainsD μ, μ ≥ 1, are investigated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 58 (1981), S. 309-330 
    ISSN: 1432-2234
    Schlagwort(e): Catchment regions ; Potential energy surfaces ; Reaction paths ; Chemical structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The space of internal coordinates of a molecular system is partitioned into catchment regions of various critical points of the energy hypersurface. The partitioning is based on an ordering of steepest descent paths into equivalence classes. The properties of these catchment regions and their boundaries are analyzed and the concepts of chemical structure, reaction path and reaction mechanism are discussed within the framework of the Born-Oppenheimer and energy hypersurface approximations. Relations between catchment regions and the chemically important reactive domains of energy hypersurfaces, as well as models for “branching” of reaction mechanisms, caused by instability domainsD μ, μ ≥ 1, are investigated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 79 (1991), S. 379-387 
    ISSN: 1432-2234
    Schlagwort(e): Shape analysis ; Lattice animals ; Similarity ; Complexity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An equivalence relation on square-cell configurations, which we call animals, is formulated precisely, using the similarity criterion of “seeing” parts of the shape of the animal from its interior, and an operation called “squashing”, leading to a smaller animal. It is noted that there is a unique smallest animal in each resulting equivalence class, called the canonical animal of its class. It is proposed that the number of cells in a canonical animalA serves as a measure of complexity of any animal similar toA. The formulation of the canonical animal is suggested as a tool for characterizing shapes of monolayer clusters of adsorbed molecules on square lattices, a problem of importance in chemical catalysis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 91 (1995), S. 67-71 
    ISSN: 1432-2234
    Schlagwort(e): T-hull ; Shape analysis ; Solvent-solute interactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary TheT-hull of both discrete point sets and continua is a generalization of the convex hull with respect to a reference objectT. VariousT-hulls serve as tools for shape analysis and as a basis for the introduction of a family of shape similarity measures. Some potential applications of these measures to shape problems arising in the natural sciences and a specific chemical example are discussed. The method ofT-hulls is applicable for the description of molecular shape effects in solvent-solute interactions, in external electromagnetic fields and within enzyme cavities.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 54 (1980), S. 95-111 
    ISSN: 1432-2234
    Schlagwort(e): Potential energy surfaces ; Reaction paths ; Transition states
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Special properties of the Riemannian metric for energy hypersurfaces, defined within the framework of the Born-Oppenheimer approximation, are utilized in devising a partitioning scheme for domains of nuclear coordinates. The chemically important coordinate domains are distinguished from domains of lesser importance by their curvature properties. Conditions are derived for the stability of minimum energy reaction paths, and the effects of instability regions are investigated. Instability domains along minimum energy paths may allow small vibrational perturbations to alter the outcome of the chemical reaction.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 54 (1980), S. 95-111 
    ISSN: 1432-2234
    Schlagwort(e): Potential energy surfaces ; Reaction paths ; Transition states
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Special properties of the Riemannian metric for energy hypersurfaces, defined within the framework of the Born-Oppenheimer approximation, are utilized in devising a partitioning scheme for domains of nuclear coordinates. The chemically important coordinate domains are distinguished from domains of lesser importance by their curvature properties. Conditions are derived for the stability of minimum energy reaction paths, and the effects of instability regions are investigated. Instability domains along minimum energy paths may allow small vibrational perturbations to alter the outcome of the chemical reaction.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Structural chemistry 6 (1995), S. 261-270 
    ISSN: 1572-9001
    Schlagwort(e): Shape analysis ; shape group method ; shape globe folding map ; macromolecular electron densities
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Macromolecular shape analysis, an important aspect of the interpretation and prediction of biochemical behavior, pharmaceutical drug action, and the properties of advanced materials, is a task of a high level of complexity, where both global shape features and detailed, local shape features are relevant. The methods developed for the study of shapes of small molecules, in terms of molecular isodensity contours (MIDCOs), are not ideally suited for large molecular systems. In particular, the shape analysis of ab initio quality macromolecular electron densities, obtained by the MEDLA (molecular electron density lego assembler) method, requires a new approach. In this contribution, the adaptation of the earlier shape group approach to the electron densities of large molecules, and two new techniques, the shape globe folding map and the self-avoiding MIDCO methods, will be described.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 185-196 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Local coordinate systems are introduced into open sets of topological spaces, defined for the nuclear configuration space R of polyatomic nuclear systems. The open sets are directly related to common chemical concepts, such as chemical structure, reaction mechanism, and stability of reaction paths. A topological model of molecules and chemical reactions is a generalization of the geometrical model, and is particularly suitable to account for the nonrigid nature of chemical structures. The coordinate neighborhoods defined on R and on its submanifolds represent the extent and natural limits for partial analyses of multidimensional potential surfaces.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 24 (1983), S. 523-526 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Boundaries of electronic energy level sets in the nuclear charge space wZ can be parametrized as single valued functionals for any nuclear geometry of molecules, which property, combined with the general convexity of such level sets, leads to various electronic energy inequalities.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 267-272 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In a previous study an energy criterion has been applied for the simplification of the enumeration problem of various conformers of biomolecules. In the present note, the above energy criterion is combined with a spatial criterion that in general leads to a reduction in the size of those domains of biomolecule potential surfaces within which the search for chemically important conformers is warranted. The above model and the conformational domains of primary interest can be formulated in a hyperspherical representation. Advantages and disadvantages of representing biomolecule potential surfaces in terms of hyperspherical coordinates are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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