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Abstract
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| The LiNC-LiCN isomerization reaction is simulated by molecular dynamics. An isolated molecule with null total angular momentum is considered. The simplificd, two degrees of freedom, intramolecular dynamics is traced out by means of the classical mechanics approximation, freezing the C-N bond to the equilibrium position. The resulting molccular model consists of a stretching coordinate of the Li atom with rcspect to the center of mass of the CN, and a bending, i.e. the reaction coordinate, of the Li atom around it. The potential energy surface of this simplified model presents two wells corresponding to the LiNC and LiCN isomers. The isomerization reaction is defined in the configuration space by those trajectories connecting the bottom regio n of the two potential wells, therefore accounting for many barrier re-crossings. The microcanonical reaction rate laws are investigated analyzing the reactant life time cumulative distributions of the ensamble using a Monte-Carlo method, and are expressed as a two term expansion of Zipf-Mandelbrot distributions [1, 2]. Therefore, several complex reaction mechanisms are identified, related to the mixed phase space structure (co-existence of KAMtori, cantori and chaotic regions, see figure 1) of the system. Consequently, non integer reaction orders for the unimolecular forward and backward reactions are found. Finally, the reaction rates as a function of the reactant concentrations are calculated averaging the isomerization time distributions. | |
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International
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No |
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Congress
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No Lineal 2008 |
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960 |
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Place
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Barcelona (España) |
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Reviewers
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Si |
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ISBN/ISSN
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978-84-96736-48-1 |
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Start Date
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16/06/2008 |
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End Date
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19/06/2008 |
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From page
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176 |
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To page
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176 |
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Nolineal 2008 |