title: Direct Dynamics Implementation of the Least-Action Tunneling Transmission Coefficient. Application to the CH4/CD3H/CD4 + CF3 Abstraction Reactions.
abstract: We present two new direct dynamics algorithms for calculating transmission coefficients of polyatomic chemical reactions by the multidimensional least-action tunneling approximation. The new algorithms are called the interpolated least-action tunneling method based on one-dimensional interpolation (ILAT1D) and the double interpolated least-action tunneling (DILAT) method. The DILAT algorithm, which uses a one-dimensional spline under tension to interpolate both of the effective potentials along the nonadiabatic portions of tunneling paths and the imaginary action integrals as functions of tunneling energies, was designed for the calculation of multidimensional LAT transmission coefficients for very large polyatomic systems. The performance of this algorithm has been tested for the CH4/CD3H/CD4 + CF3 hydrogen abstraction reactions with encouraging results, i.e., when the fitting is performed using 13 points, the algorithm is about 30 times faster than the full calculation with deviations that are smaller than 5%. This makes direct dynamics least-action tunneling calculations practical for larger systems, higher levels of electron correlation, and/or larger basis sets.
authors.affiliation: Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain and Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431.
authors.forename: Rubén
authors.initials: R
authors.lastname: Meana-Pañeda
authors.affiliation: Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain and Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431.
authors.forename: Donald G
authors.initials: DG
authors.lastname: Truhlar
authors.affiliation: Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain and Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431.
authors.forename: Antonio
authors.initials: A
authors.lastname: Fernández-Ramos