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.

The N2–N2 system: An experimental potential energy surface and calculated rotovibrational levels of the molecular nitrogen dimer

Abstract: An accurate new representation for the potential energy surface for the N2–N2 dimer has been obtained from the analysis of scattering experiments from our laboratory, and of available second virial coefficient data. A harmonic expansion functional form describes the salient geometries of the dimer and accounts for the relative contributions to the intermolecular interaction from components of different nature. The equilibrium geometry is a T conformation with well depth 13.3 meV (107.14 cm−1) and at a distance of 4.03 A. In order to assist in the analysis of spectra, we calculated the bound rotovibrational states for the (N2)2 system for J⩽6 by solving a secular problem over the exact Hamiltonian, considering the N2 monomers as rigid rotors, and where the Coriolis coupling is included.

Properties of Chemically Interesting Potential Energy Surfaces

Abstract: 1 Guidelines in the Development of the Theory of Chemical Reactivity using the Potential Energy Surface (PES) Concept.- 1.1 The Potential Energy Surface (PES) Concept.- 1.2 The Dimensionality Problem.- 1.3 On the Definition of a Reaction Path (RP).- 1.4 The Hierarchy and Competition of Reaction Theories.- 1.5 What about the Calculation of Absolute Reaction Rates?.- 1.6 Potential Energy Calculation and Gradient Revolution.- 1.7 The "State of the Art" in Everyday Study of Chemical Reactivity.- References.- 2 Analysis of Multidimensional Potential Energy Surfaces - Stationary and Critical Points.- 2.1 Basic Definitions and Notations.- 2.2 Geometrical Properties of PES.- 2.3 Stationary Points.- 2.4 Location of Stationary Points.- 2.4.1 The Newton Process and its Modifications.- 2.4.2 Update Methods.- 2.4.3 Quasi-Newton Methods.- 2.4.4 Descent Methods.- 2.4.5 A Global Newton-like Method.- 2.5 Testing of Numerical Procedures.- 2.6 Zero Eigenvalues of the Hessian.- 2.6.1 Translational and Rotational Invariance.- 2.6.2 "True" Zero Eigenvalues: Catastrophe Points.- 2.6.3 Flat Bottoms and Double Minimum Potentials.- References.- 3 Analysis of Multidimensional Potential Energy Surfaces - Paths -.- 3.1 the Simple Valley Floor Line.- 3.2 Mathematics of Valley Floors.- 3.2.1 Gradient Extremals (GE).- 3.2.2 GE and Bifurcation Points.- 3.2..3 GE for Higher-Dimensional Cases.- 3.3 Steepest Descent Paths.- 3.4 The Independence of Steepest Descent Paths from Parameterization and Coordinate System.- 3.4.1 Parameterization.- 3.4.2 Invariance from Coordinate System.- 3.4.3 Mass-Weighted Cartesian Coordinates.- References.- 4 Quantum Chemical Pes Calculations: The Proton Transfer Reactions.- 4.1 The Problem in Visualization of PES Properties.- 4.1.1 RP Energy Profiles and Surfaces Derived from Usual PES Sections.- 4.1.2 Graphical Presentation of Three-center Problems.- 4.1.3 Interaction Surface of an Attacking Species with a Fixed Valence System.- 4.1.4 Empirically Derived Diagrams of more Complex Reactions PES.- 4.1.5 Energy Profiles from Mathematically Defined RP Calculations.- 4.1.6 Summary.- References.- 4.2 PES Properties Along the Bimolecular Single Proton Transfer.- 4.2.1 Formulation of the Reaction Mechanisms.- 4.2.2 The Proton Transfer Energy.- 4.2.3 Discussion of most Recent PES Data of Bimolecular Single Proton Transfer.- 4.2.4 Gas-Phase Results and Medium Influenced Experimental Data.- 4.2.5 Theoretical Approach to Medium Influence and the PES Concept.- 4.2.6 Proton Transfer, Transition State Theory, and Quantum Chemistry.- References.

Ab initio potential energy surface for the nitrogen molecule pair and thermophysical properties of nitrogen gas

Abstract: A four-dimensional potential energy hypersurface (PES) for the interaction of two rigid nitrogen molecules was determined from high-level quantum-chemical ab initio computations. A total of 408 points for 26 distinct angular configurations were calculated utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory and basis sets up to aug-cc-pV5Z supplemented with bond functions. The calculated interaction energies were extrapolated to the complete basis set limit and complemented by corrections for core–core and core–valence correlations, relativistic effects and higher coupled-cluster levels up to CCSDT(Q). An analytical site–site potential function with five sites per nitrogen molecule was fitted to the interaction energies. The PES was validated by computing second and third pressure virial coefficients as well as shear viscosity and thermal conductivity in the dilute-gas limit. An improved PES was obtained by scaling the CCSDT(Q) corrections for all 408 points by a con...

The Ground and Excited State Hydrogen Transfer Potential Energy Surface in 7-Azaindole

Abstract: Multireference wave functions, augmented by second-order perturbation theory, are used to examine the hydrogen transfer process in the ground and first excited states of 7-azaindole and in the 1:1 7-azaindole:water complex The presence of one water molecule dramatically reduces the barrier to proton transfer in both electronic states In the excited state the order of the two tautomers is reversed, and the barrier for the hydrogen transfer from the (now higher energy) normal structure to the tautomer in the presence of one water is estimated to be ≤6 kcal/mol

Surveying a potential energy surface by eigenvector-following

Abstract: We have developed a method to search potential energy surfaces which avoids some of the difficulties associated with trapping in local minima. Steps are directly taken between minima using eigenvector-following. Exploration of this space by low temperature Metropolis Monte Carlo is a useful global optimisation tool. This method successfully finds the lowest energy icosahedral minima of Lennard- Jones clusters from random starting configurations, but cannot find the global minimum in a reasonable time for difficult cases such as the 38-atom Lennard-Jones cluster where the face-centred-cubic truncated octahedron is lowest in energy. However, by performing searches at higher temperatures, we have found a pathway between the truncated octahedron and the lowest energy icosahedral minima. Such a pathway may be illustrative of some of the structural transformations that are observed for supported metal clusters by electron microscopy.