Topological aspects of chemical reactivity. Correlation diagrams and overlap determinant method

1986 ◽  
Vol 51 (9) ◽  
pp. 1834-1842 ◽  
Author(s):  
Robert Ponec
Keyword(s):  
Chemical Reactions ◽  
Chemical Reactivity ◽  
Alternative Means

The recently proposed overlap determinant method is applied as an alternative means of construction of correlation diagrams. In comparison with existing techniques the main advantage of the proposed formalism lies above all in its universality allowing the unified classification of all types of chemical reactions.

Topological aspects of chemical reactivity. On the similarity of molecular structures

1987 ◽  
Vol 52 (3) ◽  
pp. 555-562 ◽  
Author(s):  
Robert Ponec
Keyword(s):  
Electron Density ◽  
Chemical Reactions ◽  
Chemical Reactivity ◽  
Similarity Index ◽  
Molecular Structures ◽  
Similarity Criteria ◽  
Topological Similarity

A topological similarity index is introduced, allowing to characterize quantitatively the extent of reorganization of electron density in the course of chemical reactions. The possible application of this new index for the description and the classification of chemical reactions is discussed on the basis of certain analogy of similarity criteria with the so-called least-motion principle.

Epitaxy and Chemical Reactions During Thin Film Formation from Low Energy Ions New Kinetic Pathways, New Phases and New Properties

1991 ◽  
Vol 236 ◽  
Author(s):  
Nicole Herbots ◽  
O.C. Hellman ◽  
O. Vancauwenberghe
Keyword(s):  
Thin Film ◽  
Chemical Reactions ◽  
Degrees Of Freedom ◽  
Film Growth ◽  
Film Formation ◽  
Chemical Reactivity ◽  
Ion Beam ◽  
Low Energy ◽  
Low Energy Ions ◽  
Beam Deposition

AbstractThree important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of material into a substrate, the enhancement of atomic mobility in the subsurface, and the modification of growth kinetics it creates. All lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. The fundamental understanding and new applications of low temperature kinetics induced by low energy ions in thin film growth and surface processing of semiconductors are reviewed. It is shown that the mechanism of IBD growth can be understood and computed quantitatively using a simple model including ion induced defect generation and sputtering, elastic recombination, thermal diffusion, chemical reactivity, and desorption The energy, temperature and dose dependence of growth rate, epitaxy, and chemical reaction during IBD is found to be controlled by the net recombination rate of interstitials at the surface in the case of epitaxy and unreacted films, and by the balance between ion beam decomposition and phase formation induced by ion beam generated defects in the case of compound thin films. Recent systematic experiments on the formation of oxides and nitrides on Si, Ge/Si(100), heteroepitaxial SixGe1−x/Si(100) and GaAs(100) illustrate applications of this mechanism using IBD in the form of Ion Beam Nitridation (IBN), Ion Beam Oxidation (IBO) and Combined Ion and Molecular beam Deposition (CIMD). It is shown that these techniques enable (1) the formation of conventional phases in conditions never used before, (2) the control and creation of properties via new degrees of freedom such as ion energy and lowered substrate temperatures, and (3) the formation of new metastable heterostructures that cannot be grown by pure thermal means.

An Efficient Algorithm for Automating Classification of Chemical Reactions into Classes in Ugi’s Reaction Scheme

2013 ◽  
pp. 285-296
Author(s):  
Sanjay Ram ◽  
Somnath Pal
Keyword(s):  
Chemical Reactions ◽  
Efficient Algorithm ◽  
Time Complexity ◽  
Symmetric Matrix ◽  
Reaction Scheme ◽  
Space Complexity ◽  
Average Case ◽  
Model Driven ◽  
Reaction Matrix

There are two approaches for classification of chemical reactions: Model-Driven and Data-Driven. In this paper, the authors develop an efficient algorithm based on a model-driven approach developed by Ugi and co-workers for classification of chemical reactions. The authors’ algorithm takes reaction matrix of a chemical reaction as input and generates its appropriate class as output. Reaction matrices being symmetric, matrix implementation of Ugi’s scheme using upper/lower tri-angular matrix is of O(n2) in terms of space complexity. Time complexity of similar matrix implementation is O(n4), both in worst case as well as in average case. The proposed algorithm uses two fixed size look-up tables in a novel way and requires constant space complexity. Time complexity both in worst and average cases of the algorithm is linear.

Achieving tunable chemical reactivity through photo-initiation of energetic materials at metal oxide surfaces

2020 ◽  
Vol 22 (43) ◽  
pp. 25284-25296
Author(s):  
Maija M. Kuklja ◽  
Roman Tsyshevsky ◽  
Anton S. Zverev ◽  
Anatoly Mitrofanov ◽  
Natalya Ilyakova ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Chemical Reactions ◽  
Energetic Materials ◽  
Chemical Reactivity ◽  
Energetic Material ◽  
Oxide Surfaces ◽  
Oxide Interfaces ◽  
Metal Oxide Surfaces

Photo-stimulated chemical reactions in energetic materials can be highly controlled by selectively designing energetic material – metal oxide interfaces with tailored properties.

Modelling of chemical reactions in hypersonic rarefied flow with the direct simulation Monte Carlo method

1996 ◽  
Vol 312 ◽  
pp. 149-172 ◽  
Author(s):  
Michael A. Gallis ◽  
John K. Harvey
Keyword(s):  
Monte Carlo ◽  
Chemical Reactions ◽  
Energy Exchange ◽  
Chemical Reactivity ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Rarefied Flows ◽  
Exchange Processes ◽  
Simulation Monte Carlo

In this paper the phenomenon of chemical reactivity in hypersonic rarefied flows is examined. A new model is developed to describe the reactions and post-collision energy exchange processes that take place under conditions of molecular non-equilibrium. The new scheme, which is applied within the framework of the direct simulation Monte Carlo (DSMC) method, draws its inspiration from the principles of maximum entropy which were developed by Levine & Bernstein. Sample hypersonic flow fields, typical of spacecraft re-entry conditions in which reactions play an important role, are presented and compared with results from experiments and other DSMC calculations. The latter use traditional methods for the modelling of chemical reactions and energy exchange. The differences are discussed and evaluated.

Science and creativity

2020 ◽  
Author(s):  
Flavia Bruno
Keyword(s):  
Chemical Reactions ◽  
Scientific Conference ◽  
Scientific Terminology ◽  
Educational Standard ◽  
The Earth ◽  
Hands On ◽  
Earth Structures ◽  
Lithospheric Plates ◽  
Living Organisms

<p>I teach Natural Sciences in a Liceo Artistico, a type of secondary school in Italy. It is designed to give students the skills to progress to any university, but specifically devoted to art related topics.<br>During my career I have been following the national educational standard of the Ministero dell’Istruzione, dell’Università e della Ricerca of my Country.<br>During the years students are involved in meaningful hands-on activities   such as the study of the rocks in the country, preparation of easy chemical reactions and observations through a microscope of vegetal and animal organisms. These last ones are very interesting in a Liceo Artistico where many topics focus on the study of the morphology.<br>The theory confirms what the students learn during the practical activities, furthermore it is important to acquire a correct scientific terminology as well as to be able to express scientific issues.<br>I teach during the year the following main topics:<br>Science of Earth: the Solar System, the two motions of the Earth, structures of the Earth surface (rivers, lakes, glaciers, oceans and seas), the Earth’s Spheres, the movement of lithospheric plates.<br>Biology: the characteristics and functions of living organisms especially the cells and the biodiversity. The Evolution, Mendel’s genetic laws, organism-environment relationship in order to valorize and to maintain the biodiversity. Chemistry: state of matter, classification of matter, the Mendeleev’s Periodic Table, the main chemical reactions, atomics models, chemical bonds, chemical nomenclature.<br>The extra-curricular course proposal of my school (POFT-Piano dell’Offerta Formativa Triennale) includes my project whose title is “Science and creativity”. The achievement is to create a link between scientific subjects and the art ones in order to approach knowledge which appear distant but have really many points to share.<br>Every year some classrooms study different topics such as the Nanoparticles, Biomimetic and this year the Adaptations of the animals.<br>After a scientific conference, plastic models and graphic drawings will be realised by the students, who starting from the scientific reality, can express their creativity.<br>During the years I organize some educational visits for example to the Botanic Garden as well as to the countryside; in this way the students have opportunities to create an e-book with texts and photographs.<br>For instance two years ago my classroom created an e-book with botanical cards and the following year another one with the title “Rocce a Milano” where students took pictures and texts about this topic.<br>Many classrooms and teachers are involved in this project for example Plastic and Drawing teachers, as well as Multimedia teachers. I manage to gather the interested teachers and to realize the projects.<br>With our productions we participate in competitions and we are sometimes selected.</p>

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