Calculus of variations as a basic tool for modelling of reaction paths and localisation of stationary points on potential energy surfaces

Bofill, Josep María; Quapp, Wolfgang

doi:10.1080/00268976.2019.1667035

Cited by 10 publications

(7 citation statements)

References 64 publications

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“…This gap can indicate that the dipole of the molecule inhibits the application of an electric field into a desired direction. This situation emerges for many proposed putative “reaction pathways”, which are not steepest descent or NTs, − and it holds also for the often treated GEs. ,,, Therefore, a conclusion of this section will be that we must always calculate the FDSPs associated to the optimal e n * , viz., we must check that the curve of FDSPs connects the minimum with the searched SP 1 , as well as with the global goal, i.e., the next product minimum. ,, …”

Section: A Thorough Discussion Of the Main Geometrical Aspects Of The...mentioning

confidence: 99%

Controlling Chemical Reactivity with Optimally Oriented Electric Fields: A Generalization of the Newton Trajectory Method

Bofill

Quapp

Albareda

et al. 2022

J. Chem. Theory Comput.

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The use of oriented external electric fields (OEEF) as a tool to accelerate chemical reactions has recently attracted much interest. A new model to calculate the optimal OEEF of the least intensity to induce a barrierless chemical reaction path is presented. A suitable ansatz is provided by defining an effective potential energy surface (PES), which considers the unperturbed or original PES of the molecular reactive system and the action of a constant OEEF on the overall dipole moment of system. Based on a generalization of the Newton Trajectories (NT) method, it is demonstrated that the optimal OEEF can be determined upon locating a special point of the potential energy surface (PES), the so-called "optimal bond-breaking point" (optimal BBP), for which two different algorithms are proposed. At this point, the gradient of the original or unperturbed PES is an eigenvector of zero eigenvalue of the Hessian matrix of the effective PES. A thorough discussion of the geometrical aspects of the optimal BBP and the optimal OEEF is provided using a two-dimensional model, and numerical calculations of the optimal OEEF for a S N 2 reaction and the 1,3-dipolar retrocycloaddition of isoxazole to fulminic acid plus acetylene reaction serve as a proof of concept. The knowledge of the orientation of optimal OEEF provides a practical way to reduce the effective barrier of a given chemical process.

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Section: A Thorough Discussion Of the Main Geometrical Aspects Of The...mentioning

confidence: 99%

Controlling Chemical Reactivity with Optimally Oriented Electric Fields: A Generalization of the Newton Trajectory Method

Bofill

Quapp

Albareda

et al. 2022

J. Chem. Theory Comput.

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“…Another well-known problem, which requires a sequential switching approach with maximum automation and minimal, but intuitive interaction, is the search for transition states (TS), i.e., first-order saddle points on a PES. Numerous stable and reliable TS optimization algorithms have been developed in the last fifty years [381][382][383]. However, due to the difficult nature of the optimization problem, a universally successful algorithm that is able to find all relevant TS from a limited number of start conformations will most likely never exist.…”

Section: Workflows For Efficient Computation Protocolsmentioning

confidence: 99%

Autonomous Reaction Network Exploration in Homogeneous and Heterogeneous Catalysis

Steiner

Reiher

2022

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Autonomous computations that rely on automated reaction network elucidation algorithms may pave the way to make computational catalysis on a par with experimental research in the field. Several advantages of this approach are key to catalysis: (i) automation allows one to consider orders of magnitude more structures in a systematic and open-ended fashion than what would be accessible by manual inspection. Eventually, full resolution in terms of structural varieties and conformations as well as with respect to the type and number of potentially important elementary reaction steps (including decomposition reactions that determine turnover numbers) may be achieved. (ii) Fast electronic structure methods with uncertainty quantification warrant high efficiency and reliability in order to not only deliver results quickly, but also to allow for predictive work. (iii) A high degree of autonomy reduces the amount of manual human work, processing errors, and human bias. Although being inherently unbiased, it is still steerable with respect to specific regions of an emerging network and with respect to the addition of new reactant species. This allows for a high fidelity of the formalization of some catalytic process and for surprising in silico discoveries. In this work, we first review the state of the art in computational catalysis to embed autonomous explorations into the general field from which it draws its ingredients. We then elaborate on the specific conceptual issues that arise in the context of autonomous computational procedures, some of which we discuss at an example catalytic system. Graphical Abstract

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“…We use a first variational structure of the SEGO model where g ( r ) is the gradient of the PES, s is the Lagrange multiplier, and ϕ ( r ) is the derivation of the extra term ϕ ( r ) = ∇ r ( f ( r ) T r ). If we assume that ϕ ( r ) ≠ 0 , we can write the variation ansatz in another form where U is the unit matrix.…”

Section: Sego Curves By a Variational Formulamentioning

confidence: 99%

Comment on “Exploring Potential Energy Surface with External Forces”

Quapp

Bofill

2019

J. Chem. Theory Comput.

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Enforced Geometry Optimization) was proposed to find new minimums on potential energy surfaces. We study this important method from a theoretical point of view. Up to date, the understanding of the proposer does not take into account the barrier breakdown point on a SEGO path being usually half of the path which is searched for. However, a better understanding of the method allows us to follow along the reaction pathway from a minimum to a saddle point, or vice versa. We discuss the well-known two-dimensional MB-test surface where we calculate full SEGO pathways. If one has special SEGO curves at hand, one can also detect some weaknesses of the ansatz.

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Calculus of variations as a basic tool for modelling of reaction paths and localisation of stationary points on potential energy surfaces

Cited by 10 publications

References 64 publications

Controlling Chemical Reactivity with Optimally Oriented Electric Fields: A Generalization of the Newton Trajectory Method

Controlling Chemical Reactivity with Optimally Oriented Electric Fields: A Generalization of the Newton Trajectory Method

Autonomous Reaction Network Exploration in Homogeneous and Heterogeneous Catalysis

Comment on “Exploring Potential Energy Surface with External Forces”

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