Accession Number : ADA621671


Title :   Automated Discovery of New Chemical Reactions and Accurate Calculation of Their Rates


Descriptive Note : Final performance rept. 1 Mar 2013-28 Feb 2015


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE


Personal Author(s) : Green, William H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a621671.pdf


Report Date : 02 Jun 2015


Pagination or Media Count : 23


Abstract : A major challenge in combustion chemistry is to be sure that all of the important reactions have been included in the kinetic model. Experience shows that missing reactions are a major cause of discrepancies between model predictions and experimental performance. Looking at combustion chemistry as motion on a Potential Energy Surface landscape, reactions are the passes that connect valleys representing the different molecules; whether or not two valleys are connected is the key issue determining the topology of the landscape. Conventional kinetic modeling approaches include only well known types of reactions in the models; as demonstrated in this project these conventional models omit most of the actual reactions occurring in the engine. Discovering new reactions is very challenging, so historically many of the most important reactions have been discovered by serendipity (either experimentally or by using quantum chemistry). In this project we develop a much more systematic approach, using high performance computing to search for reactions connecting a specified reactant to each possible product, and using quantum chemistry to determine the reaction barriers. The algorithm developed here has 4 key steps: (1) identification of all the potential product channels ; (2) Search for a low energy reaction path connecting reactant and each product channel; and (3) refinement of the reaction path to determine the saddle point geometry and barrier height. This new computational approach is found to be the most effective method so far at discovering novel chemical reactions. Using the new algorithm we have discovered 38 new exothermic or mildly endothermic reactions in this project.


Descriptors :   *COMBUSTION , *QUANTUM CHEMISTRY , *REACTANTS(CHEMISTRY) , ALGORITHMS , CHEMICAL REACTIONS , ENDOTHERMIC REACTIONS , ETHYLENES , EXOTHERMIC REACTIONS , HIGH PERFORMANCE COMPUTING , KINETICS , LOW ENERGY , MATHEMATICAL MODELS , MATHEMATICAL PREDICTION , MOLECULAR DYNAMICS , POTENTIAL ENERGY , RESPONSE , SURFACE CHEMISTRY , TOPOLOGY


Subject Categories : Physical Chemistry
      Atomic and Molecular Physics and Spectroscopy
      Quantum Theory and Relativity
      Combustion and Ignition


Distribution Statement : APPROVED FOR PUBLIC RELEASE