**************第２１回尾張コンプレックスセミナー******************************



題　目：　Studying Microscopic Reaction Mechanisms by QM, QM+MM, 

　　　　　and QM/MM Direct Dynamics Simulations



発表者：　Prof. William L. Hase (Texas Tech University) 



日　時:　２月２３日（月)  １３時００分～

  　　  　　

場　所：　情報科学研究科1階第2講義室



内　容：　In a direct dynamics simulation all or part of the potential

　　　　energy surface for a chemical reaction is represented by a quantum

　　　　mechanical (QM) electronic structure theory.  The feasibility of these

　　　　studies has made it possible to investigate how atoms actually move on a

　　　　potential energy surface and to determine atomic-level mechanisms for a

　　　　broad range of reactions.  For a reaction with many atoms, the potential

　　　　energy for a subset of the atoms may be represented by molecular mechanical

　　　　(MM) analytic potential energy functions.  In this talk several recent

　　　　direct dynamics simulations which have provided new understandings of

　　　　reaction mechanisms will be reviewed.  Simulations of gas-phase SN2

　　　　reactions have illustrated the need to go beyond the reaction path model to

　　　　describe chemical reactions, protonated peptide ions may undergo

　　　　surface-induced dissociation (SID) by a shattering mechanism, and the

　　　　reactive collisions of high-energy triplet oxygen atoms with alkane

　　　　molecules can not be described by conventional models of chemical kinetics.



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