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.

Helicity decoupled quantum dynamics and capture model cross sections and rate constants for O(1D) + H2 → OH + H

Abstract: We study, within a helicity decoupled quantum approximation, the total angular momentum J dependence of reaction probabilities for the reaction O(1D)+H2→OH+H. A recently developed real wave packet approach is employed for the quantum calculations. The abinitio based, ground electronic (1A′) potential energy surface of Ho etal. (T-S. Ho, T. Hollebeeck, H. Rabitz, L. B. Harding and G. C. Schatz, J. Chem. Phys., 1996, 105, 10472) is assumed for most of our calculations, although some calculations are also performed with a recent surface due to Dobbyn and Knowles. We find that the low J reaction probabilities tend to be, on average, slightly lower than the high J probabilities. This effect is also found to be reproduced in classical trajectory calculations. A new capture model is proposed that incorporates the available quantum data within an orbital angular momentum or l-shifting approximation to predict total cross sections and rate constants. The results agree well with classical trajectory results and the experimental rate constant at room temperature. However, electronically non-adiabatic effects may become important at higher temperature.

Phototriggered Linkage Isomerization in Ruthenium-Dimethylsulfoxyde Complexes: Insights from Theory

Abstract: The ground and excited-state properties of [Ru(bpy)(tpy)dmso] 2 + (bpy = 2,2'-bipyridine, tpy = 2,2':6',2"-terpyridine; dmso = dimethyl sulfoxide) have been studied by the means of density functional theory (DFT). In particular, the singlet ground state and the potential energy surface of the lowest triplet were investigated along the coordinate involved in the S → O linkage isomerization of dmso. The time-dependent-DFT approach (TDDFT) was used to interpret the absorption spectra of the system, while a ΔSCF procedure was applied to compute the emission spectra. The good agreement between computed and experimental spectra highlights the power of DFT approaches in the description of complex transition metal containing systems. In addition, this method allows the full description of the ground and excited potential energy surfaces of [Ru(bpy)(tpy)-dmso] 2 + which can only be roughly derived from experimental data, thus providing clues for further improvement in the engineering of phototriggering materials.

An ab initio intermolecular potential for the carbon monoxide dimer (CO)2

Abstract: We have constructed an analytical potential energy surface for CO–CO by means of ab initio calculations for the electrostatic and first‐order exchange interactions and by the use of accurate dispersion coefficients recently calculated in our group. Parameter‐free damping functions account for second‐order exchange and penetration effects. The anisotropy of this potential is represented by an expansion in spherical harmonics for the molecules A and B, up to LA, LB=5 inclusive. The second virial coefficients calculated with this potential, including quantum corrections, lie within the experimental error bars over a wide temperature range.

Flat surface study of the Eley–Rideal dynamics of recombinative desorption of hydrogen on a metal surface

Abstract: The dynamics of a direct reaction between a gas phase H atom and an adsorbed H atom, often referred to as an Eley–Rideal mechanism, is explored using a fully three‐dimensional flat surface model for Cu(111). The model is based on a flat‐surface approximation for a single electronically adiabatic potential energy surface (PES). This reduces the inherently six‐dimensional reactive scattering problem (for a rigid surface) to a three‐dimensional problem by introducing three constants of motion. The resulting scattering problem is treated quantum mechanically by solving the time‐dependent Schrodinger equation, and also by quasiclassical trajectory calculations. We have considered four different model PESs which are all more or less compatible with available knowledge about the interactions between hydrogen atoms and molecules and Cu(111). We have studied the dependence of the reactive cross section and product translational energy and rovibrational state distributions on the kinetic energy and angle of the inc...

Mode selectivity in methane dissociative chemisorption on Ni(111)

Abstract: Dissociative chemisorption of CH4 on transition-metal surfaces, representing the rate-limiting step in methane steam reforming, has been shown experimentally to be strongly mode selective. To understand the mode selectivity, a twelve-dimensional global potential energy surface is developed for CH4 interacting with a rigid Ni(111) surface based on a large number of density functional theory points. The reaction dynamics is investigated using an eight-dimensional quantum model, which includes representatives of all four vibrational modes of methane. After correcting for surface effects, key experimental observations, including the mode selectivity, are well reproduced. These theoretical results, along with mechanistic analysis, provide insights into this industrially important heterogeneous reaction.