title: A New Method for Describing the Mechanism of a Chemical Reaction Based on the Unified Reaction Valley Approach.
abstract: The unified reaction valley approach (URVA) used for a detailed mechanistic analysis of chemical reactions is improved in three different ways: (i) Direction and curvature of path are analyzed in terms of internal coordinate components that no longer depend on local vibrational modes. In this way, the path analysis is no longer sensitive to path instabilities associated with the occurrences of imaginary frequencies. (ii) The use of third order terms of the energy for a local description of the reaction valley allows an extension of the URVA analysis into the pre- and postchemical regions of the reaction path, which are typically characterized by flat energy regions. (iii) Configurational and conformational processes of the reaction complex are made transparent even in cases where these imply energy changes far less than a kcal/mol by exploiting the topology of the potential energy surface. As examples, the rhodium-catalyzed methanol carbonization, the Diels-Alder reaction between 1,3-butadiene and ethene, and the rearrangement of HCN to CNH are discussed.
authors.affiliation: Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University , 3215 Daniel Ave, Dallas, Texas 75275-0314, United States.
authors.forename: Wenli
authors.initials: W
authors.lastname: Zou
authors.affiliation: Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University , 3215 Daniel Ave, Dallas, Texas 75275-0314, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sexton
authors.affiliation: Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University , 3215 Daniel Ave, Dallas, Texas 75275-0314, United States.
authors.forename: Elfi
authors.initials: E
authors.lastname: Kraka
authors.affiliation: Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University , 3215 Daniel Ave, Dallas, Texas 75275-0314, United States.
authors.forename: Marek
authors.initials: M
authors.lastname: Freindorf
authors.affiliation: Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University , 3215 Daniel Ave, Dallas, Texas 75275-0314, United States.
authors.forename: Dieter
authors.initials: D
authors.lastname: Cremer