Comprehensive theoretical studies on the CF3H dissociation mechanism and the reactions of CF3H with OH and H free radicals

Meiling Zhang; Zijing Lin; Ce Song
January 2007
Journal of Chemical Physics;1/21/2007, Vol. 126 Issue 3, p034307
Academic Journal
The potential energy surfaces for the CF3H unimolecular dissociation reaction and reactions of CF3H with free radical OH and H were investigated at the B3LYP/6-311++G** and QCISD(T)/6-311++G** levels and by the G3B3 theory. All the possible stationary and first-order saddle points along the reaction paths were verified by the vibrational analysis. The calculations account for all the product channels. The reaction enthalpies obtained at the G3B3 level are in good agreement with the available experiments. Canonical transition-state theory with Wigner tunneling correction was used to predict the rate constants for the temperature range of 298–2500 K without any artificial adjustment, and tshe computed rate constants for elementary channels can be accurately fitted with three-parameter Arrhenius expressions. The theoretical rate constants of the CF3H+H reaction agree with the available experimental data very well. The theoretical and experimental rate constants for the CF3H+OH reaction are in reasonable agreement. The H abstraction of CF3H by OH is found to be the main reaction channel for the CF3H fire extinguishing reactions while the CF3H unimolecular dissociation reaction plays a negligible role.


Related Articles

  • Saddle points of the potential energy surface for HCCF determined by an algebraic approach. Wang, X.; Ding, S. // European Physical Journal D -- Atoms, Molecules, Clusters & Opti;Jun2004, Vol. 29 Issue 3, p337 

    The potential energy surface of the tetratomic molecule HCCF is determined by the U(4) algebraic method. The combination coefficients in the Hamiltonian are gotten from fitting the spectroscopic data. The molecular properties, such as, force constants and dissociation energies, are obtained in...

  • Theory, Experiment and Unusual Features of Potential Energy Surfaces of Pericyclic and Pseudopericyclic Reactions with Sequential Transition Structures. Birney, David Martin // Current Organic Chemistry;Sep2010, Vol. 14 Issue 15, p1658 

    No abstract available.

  • A global ab initio potential energy surface for HNO (a3A″) and quantum mechanical studies of vibrational states and reaction dynamics. Li, Anyang; Xie, Changjian; Xie, Daiqian; Guo, Hua // Journal of Chemical Physics;5/21/2011, Vol. 134 Issue 19, p194309 

    A new global potential energy surface for the lowest triplet electronic state (a3A″) of HNO has been developed by a three-dimensional cubic spline interpolation of more than 13 000 ab initio points, which were calculated at the multireference configuration interaction level with Davidson...

  • Using swarm intelligence for finding transition states and reaction paths. Fournier, René; Bulusu, Satya; Chen, Stephen; Tung, Jamie // Journal of Chemical Physics;9/14/2011, Vol. 135 Issue 10, p104117 

    We describe an algorithm that explores potential energy surfaces (PES) and finds approximate reaction paths and transition states. A few (≈6) evolving atomic configurations ('climbers') start near a local minimum M1 of the PES. The climbers seek a shallow ascent, low energy, path toward a...

  • Ridge method for finding saddle points on potential energy surfaces. Ionova, Irina V.; Carter, Emily A. // Journal of Chemical Physics;4/15/1993, Vol. 98 Issue 8, p6377 

    A new method is proposed for locating saddle points on potential energy surfaces. The method involves walking on the ridge separating reactants’ and products’ valleys toward its minimum, which is a saddle point in coordinate space. Of particular advantage for ab initio...

  • Quadratic steepest descent on potential energy surfaces. IV. Adaptation to singular Hessians. Ruedenberg, Klaus; Sun, Jun-Qiang // Journal of Chemical Physics;4/15/1994, Vol. 100 Issue 8, p6101 

    It is shown that the quadratic steepest descent procedure developed in three previous papers goes smoothly and naturally into a limiting form, presenting no computational problems, when the Hessian becomes singular. This is in contrast to quasi-Newton algorithms which, in the case of singular or...

  • The Step and Slide method for finding saddle points on multidimensional potential surfaces. Miron, Radu A.; Fichthorn, Kristen A. // Journal of Chemical Physics;11/15/2001, Vol. 115 Issue 19, p8742 

    We present the Step and Slide method for finding saddle points between two potential-energy minima. The method is applicable when both initial and final states are known. The potential-energy surface is probed by two replicas of the system that converge to the saddle point by following...

  • Theoretical studies of the potential surface for the F+H2→HF+H reaction. Bauschlicher, Charles W.; Walch, Stephen P.; Langhoff, Stephen R.; Taylor, Peter R.; Jaffe, Richard L. // Journal of Chemical Physics;2/1/1988, Vol. 88 Issue 3, p1743 

    The F+H2→HF+H potential energy hypersurface has been studied in the saddle-point and entrance channel regions. Using a large [5s 5p 3d 2f 1g/4s 3p 2d] atomic natural orbital basis set, we obtain a classical barrier height of 1.86 kcal/mol at the CASSCF/multireference CI level (MRCI) after...

  • Finding saddle points for clusters. Wales, David J. // Journal of Chemical Physics;12/1/1989, Vol. 91 Issue 11, p7002 

    The Cerjan–Miller eigenvector-following method is highly successful in finding saddle points for a variety of clusters whose potential energy surfaces are well described using simple analytical pair potentials. Examples are given for argon clusters, including Ar33 and Ar55, potassium...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics