Journal ArticleDOI
Reliable Transition State Searches Integrated with the Growing String Method.
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TLDR
An integrated technique for simultaneous reaction path and exact transition state search is described by implementing an eigenvector following optimization algorithm in internal coordinates with Hessian update techniques.Abstract:
The growing string method (GSM) is highly useful for locating reaction paths connecting two molecular intermediates. GSM has often been used in a two-step procedure to locate exact transition states (TS), where GSM creates a quality initial structure for a local TS search. This procedure and others like it, however, do not always converge to the desired transition state because the local search is sensitive to the quality of the initial guess. This article describes an integrated technique for simultaneous reaction path and exact transition state search. This is achieved by implementing an eigenvector following optimization algorithm in internal coordinates with Hessian update techniques. After partial convergence of the string, an exact saddle point search begins under the constraint that the maximized eigenmode of the TS node Hessian has significant overlap with the string tangent near the TS. Subsequent optimization maintains connectivity of the string to the TS as well as locks in the TS direction, al...read more
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Journal ArticleDOI
Extended tight-binding quantum chemistry methods
Christoph Bannwarth,Eike Caldeweyher,Sebastian Ehlert,Andreas Hansen,Philipp Pracht,Jakob Seibert,Sebastian Spicher,Stefan Grimme +7 more
TL;DR: The xTB model as discussed by the authors is derived from a density functional (DFT) perturbation expansion of the electron density in fluctuation terms to various orders similar to the original density functional tight binding model.
Journal ArticleDOI
Methods for exploring reaction space in molecular systems
TL;DR: Several of these approaches, which are categorized based on their overarching TS finding strategies, have been described in this paper, and future advances are discussed that may revolutionize the ability of simulation to fully predict not just the reaction mechanism but reaction outcomes.
Journal ArticleDOI
Concerted nucleophilic aromatic substitutions
TL;DR: New and sensitive methodology for measuring carbon kinetic isotope effects now shows that most such substitutions actually occur through concerted mechanisms.
Journal ArticleDOI
Single-ended transition state finding with the growing string method.
TL;DR: A single‐ended growing string method (GSM) is introduced which allows for reaction path searches starting from a single structure and can be even more computationally efficient than the already rapid double‐ended method.
Journal ArticleDOI
Iron( III )-catalysed carbonyl–olefin metathesis
TL;DR: A catalytic carbonyl–olefin ring-closing metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst is demonstrated and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis.
References
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Journal ArticleDOI
Density‐functional thermochemistry. III. The role of exact exchange
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Journal ArticleDOI
Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Journal ArticleDOI
VMD: Visual molecular dynamics
TL;DR: VMD is a molecular graphics program designed for the display and analysis of molecular assemblies, in particular biopolymers such as proteins and nucleic acids, which can simultaneously display any number of structures using a wide variety of rendering styles and coloring methods.
Journal ArticleDOI
Density-functional exchange-energy approximation with correct asymptotic behavior.
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
Journal ArticleDOI
A climbing image nudged elastic band method for finding saddle points and minimum energy paths
TL;DR: In this article, a modification of the nudged elastic band method for finding minimum energy paths is presented, where one of the images is made to climb up along the elastic band to converge rigorously on the highest saddle point.
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