Topic
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.
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TL;DR: In this article, the Kolmogorov entropy for three and seven-particle clusters bound by Lennard-Jones potentials and for threeparticle cluster bound by Morse potentials of various ranges was calculated.
Abstract: We have calculated the Kolmogorov entropy for three‐ and seven‐particle clusters bound by Lennard‐Jones potentials and for three‐particle clusters bound by Morse potentials of various ranges. We have used two quite different methods, one of which is new, which give consistent results. We find that all of these systems are classically chaotic over a wide range of energies surrounding the estimated quantum‐mechanical zero point energies. Furthermore, for the three‐particle clusters, we can rationalize the variation in the degree of chaos with total energy in terms of the local structure of the clusters’ potential energy surface.
78 citations
TL;DR: A variety of model potential energy surfaces based on simple extensions to the Lennard-Jones model are presented in this paper, which include activation barriers which vary across the surface unit cell giving rise to a variety of physically interesting and realistic topologies.
Abstract: Some theoretical and experimental aspects of the interaction of H2 with metal surfaces are reviewed. A variety of model potential energy surfaces based on simple extensions to the Lennard‐Jones model are presented. These potentials include activation barriers which vary across the surface unit cell giving rise to a variety of physically interesting and realistic topologies. The quantum‐mechanical scattering of hydrogen and its isotopes from these potentials illustrate that it is possible, in a very simple way, to account for simultaneous sticking and diffraction at a single beam energy. The inclusion of tunneling in a realistic description of initial sticking coefficients is shown to be essential for these light gases. Finally, it is proposed that by inverting diffraction data, it should be possible to obtain key information regarding the form of the potential energy surface.
78 citations
TL;DR: The possibility that instead of optimizing binding to a well-defined transition- state structure, enzymes are optimized by evolution to bind efficiently with a transition-state ensemble, with a broad range of activated conformations is analysed.
78 citations
TL;DR: In this paper, the authors compare hybrid density functional theory and multi-coefficient correlation methods for locating saddle point geometries and calculating barrier heights on a Born−Oppenhiemer potential energy surface.
Abstract: We compare hybrid density functional theory and multi-coefficient correlation methods for locating saddle point geometries and calculating barrier heights on a Born−Oppenhiemer potential energy surface. We located reactant, product, and saddle point stationary points by the multi-coefficient Gaussian-3 (MCG3) method for 15 reactions, and by the multi-coefficient quadratic configuration interaction with single and double excitations (MC-QCISD) method for 22 reactions; and the resulting structures and energies are compared to those obtained by the Moller−Plesset second order perturbation theory (MP2), QCISD, and modified Perdew−Wang 1-parameter-for-kinetics (MPW1K) methods. We examined three single-level methods with two basis sets, 6-31+G(d,p) and MG3. By comparison to calculations on five systems where the saddle point has been optimized at a high level of theory, we conclude that the best saddle point geometries for the methods tested are those found at the MC-QCISD, MCG3, and MPW1K levels. MP2 was shown...
77 citations
TL;DR: In this article, a newly determined 5D potential energy surface for H2-H2O was used to provide an extended and revised set of rate coefficients for de-excitation of the lowest 10 para- and 10 ortho- rotational levels of H2O by collisions with para-(j=0) and orthoH2(j=1), for kinetic temperatures from 5 K to 20 K.
Abstract: Aims.Using a newly determined 5D potential energy surface for H2-H2O we provide an extended and revised set of rate coefficients for de-excitation of the lowest 10 para- and 10 ortho- rotational levels of H2O by collisions with para-(j=0) and ortho-H2(j=1), for kinetic temperatures from 5 K to 20 K.
Methods.Our close coupling scattering calculations involve a slightly improved set of coupled channels with respect to previous calculations. In addition, we discuss the influence of several features of this new 5D interaction on the rotational excitation cross sections.
Results. The new interaction potential leads to significantly different rate coefficients for collisions with para-H2 (j=0). In particular the de-excitation rate coefficient for the 110 to 101 transition is increased by up to 300% at 5 K. At 20 K this increase is 75%. Rate coefficients for collisions with ortho-H2(j=1) are modified to a lesser extent, by up to 40%. The influence of the new potential on collisions with both para-(j=0) and ortho-H2(j=1) is expected to become less pronounced at higher temperatures.
77 citations