“…There was a speculation on the meaning of VRI for high overtones using the example H 2 O [18]. However, it seems that it is to reject by the experimental assigns of high local modes of water.…”
Valley -ridge-inflection points (VRI) of a potential energy surface (PES) may have a strong relation to bifurcations of chemical reaction pathways. We explain how a reaction path has to be defined to describe the bifurcation of a 'valley' of the PES. We propose a classification of different VRI events: valley bifurcation, ridge bifurcation, and the mixed case in between. Chemical implications of the different cases are discussed. q
“…There was a speculation on the meaning of VRI for high overtones using the example H 2 O [18]. However, it seems that it is to reject by the experimental assigns of high local modes of water.…”
Valley -ridge-inflection points (VRI) of a potential energy surface (PES) may have a strong relation to bifurcations of chemical reaction pathways. We explain how a reaction path has to be defined to describe the bifurcation of a 'valley' of the PES. We propose a classification of different VRI events: valley bifurcation, ridge bifurcation, and the mixed case in between. Chemical implications of the different cases are discussed. q
“…where m is the step number [9,10,25,29,32]. A m is the adjoint matrix of the Hessian and g m is the gradient at point x m .…”
Section: Branin's Methods To Calculate Symmetric Valley-ridge Inflectimentioning
confidence: 99%
“…It is an uncertainty of the RP definition, how a reaction path ascends to the SP. We use here the distinguished or driven coordinate method [7] in the modern form of RGF [8][9][10][11][12][13].…”
The reaction path is an important concept of theoretical chemistry. We discuss the definition with the help of the following of the reduced gradient (RGF) [see Quapp et al., Theoret. Chem. Acc. 100 (1998) 285], also named the Newton trajectory. All the important features of the potential energy surface are definable independently of the coordinate system. We demonstrate it for the Newton trajectory. We design a numerical scheme for the RGF method including the intrinsic curvilinear metric of internal coordinates. For the path following we extend the previous method to the use of a generalized singular value decomposition (SVD). An example of the HCN isomerization pathway is discussed.
“…We note that there exists a long list of theoretical developments, 4-7,9-13,19-30 as well as of applications of NTs in Chemistry. [31][32][33][34][35][36][37][38] We can, on the other hand, start with the simplest definition of an NT that the gradient lies in a fixed 1-dimensional subspace 18 or that the gradient of the PES along the curve always points into a given direction:…”
Section: Newton: Trajectories and Homotopymentioning
confidence: 99%
“…Pieces of the manifold of VRI points were already often found on the PES of small molecules. A successful search is reported of VRI regions for the molecules H 2 O, 31 . 38 The approximation of asymmetric VRI points on the PES was already solved elsewhere.…”
We show that the Newton homotopy used in the paper [D. Mehta et al., J. Chem. Phys. 142, 194113 (2015)] is related to the Newton trajectory method. With the theory of the Newton trajectories at hand, we can sharpen some findings of the paper.
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