Potential energy surface

About: Potential energy surface is a research topic. Over the lifetime, 11674 publications have been published within this topic receiving 307691 citations.

Quasiclassical state to state reaction cross sections for D+H2(v=0, j=0)→HD(v’,j’)+H. Formation and characteristics of short‐lived collision complexes

Abstract: State resolved total and differential reaction cross sections, as well as reaction probabilities, have been calculated by the quasiclassical trajectory (QCT) method for the D+H2(v=0, j=0)→HD(v’,j’)+H reaction on the Liu–Siegbahn–Truhlar–Horowitz potential energy surface in the collision energy range 0.30–1.25 eV. Thus a detailed comparison with existing fully converged quantum mechanical (QM) calculations has been performed. The general agreement between both sets of results is good with some differences. QCT integral reaction cross sections for the production of HD(v’=0) are lower than the corresponding QM ones by 10%–15% for collision energies higher than 0.6 eV, and the energy dependence of the QCT reaction probability with a total angular momentum J equal to zero shows no structure when summed over all j’ states (contrary to the QM case). The differential cross sections for the lowest j’ values show, when represented as a function of energy, a ‘‘ridge’’ feature similar to the one found in exact QM cal...

Experimental determination of quantum state resolved differential cross sections for the hydrogen exchange reaction H+D2→HD+D

Abstract: We have carried out a systematic crossed molecular beam study of the hydrogen exchange reaction in the H+D2→HD+D isotopic form at two collision energies: 0.53 and 1.28 eV. The Rydberg atom time-of-flight method was used to measure the D-atom product angle-velocity distribution. For the first time ro-vibrational quantum state resolved differential cross sections for the title reaction were measured, which can directly be compared to theoretical predictions at this detailed level. Experimental results are compared to theoretical predictions from both quasi classical and quantum mechanical calculations on different potential energy surfaces as well as to earlier experiments. A general good agreement is found for the converged quantum mechanical calculations with indications that the Boothroyd-Keogh-Martin-Peterson potential energy surface is better suited to describe the dynamics of the reaction. For the higher collision energy the quasi classical trajectory calculations reproduce the experimental data quite well, whereas they fail to describe the situation at the lower collision energy especially with respect to angular resolved differential cross sections.

Transport Theory for Cationic Zeolites: Diffusion of Benzene in Na-Y

Abstract: We have modeled benzene diffusion in Na-Y zeolite (%:A1 = 2.0) over the temperature range 100-500 K. We apply the kinetic Monte Carlo random walk model, with activation energies derived from a new zeolitehydrocarbon potential energy surface (PES). An Arrhenius fit yields the apparent activation energy E, = 41 kJ mol-’, as compared with the previously determined experimental values 14-27 kJ mol-’. Minimum energy paths from the new PES demonstrate “cartwheel” and “skateboard” hopping mechanisms for benzene in Na-Y. Analysis of the results suggests that activation energies from long length scale diffusion measurements, e.g. pulsed field gradient NMR, should be interpreted as site-to-window activation energies, whereas those from short length scale experiments, e.g. spin-lattice relaxation NMR, correspond to intracage site-to-site activation energies. I. Introduction The structural, thermochemical, and dynamical properties of adsorbed hydrocarbons play a central role in catalytic processes that take place within the cavities of zeolites and other shapeselective, microporous catalysts. Selectivity, for example, may be strongly influenced by the diffusivities of reactant and product molecules. Computational studies have made a significant impact in this area during the last 10 years, helping to elucidate zeolite framework structure,’ hydrocarbon sorbate dynamics: and catalytic

How Does Fe+ Activate C−C and C−H Bonds in Ethane? A Theoretical Investigation Using Density Functional Theory†

Abstract: The potential energy surface (PES) corresponding to the reaction of the iron cation with ethane, which represents a prototype of the activation of C−C and C−H bonds in alkanes by transition metal cations, has been investigated employing the recently suggested hybrid density functional theory/Hartree−Fock method (B3LYP) combined with reasonably large one-particle basis sets. The performance of this computational approach has been calibrated against experimentally known Fe+−R binding energies of fragments R relevant to the [Fe,C2,H6]+ PES and against the relative energies of the possible exit channels. Both the C−C and C−H bond activation branches of the PES are characterized by a low barrier for the first step, the insertion of the iron cation into a C−C and C−H bond, respectively. Rate determining are the second steps which in the C−C bond activation branch corresponds to an [1,3]-H shift leading to a complex between FeCH2+ and methane. Along the C−H activation reaction coordinate, no transition state cor...