Interpolating moving least-squares methods for fitting potential energy surfaces: Computing high-density potential energy surface data from low-density ab initio data points

2007 ◽  
Vol 126 (18) ◽  
pp. 184108 ◽  
Author(s):  
Richard Dawes ◽  
Donald L. Thompson ◽  
Yin Guo ◽  
Albert F. Wagner ◽  
Michael Minkoff
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Moving Least Squares ◽  
Low Density ◽  
Surface Data ◽  
Data Points ◽  
Energy Surfaces

Collisional excitation of CH(X2Π) by He: new ab initio potential energy surfaces and scattering calculations

2015 ◽  
Vol 17 (33) ◽  
pp. 21583-21593 ◽  
Author(s):  
Sarantos Marinakis ◽  
Indigo Lily Dean ◽  
Jacek Kłos ◽  
François Lique
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Experimental Results ◽  
Collisional Excitation ◽  
Energy Surfaces

We present a new CH(X)–He potential energy surface which is able to reproduce all the available experimental results.

Collisional excitation of interstellar PO(X2Π) by He: new ab initio potential energy surfaces and scattering calculations

2018 ◽  
Vol 20 (8) ◽  
pp. 5407-5414 ◽  
Author(s):  
François Lique ◽  
Izaskun Jiménez-Serra ◽  
Serena Viti ◽  
Sarantos Marinakis
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Inelastic Scattering ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Quantum Scattering ◽  
Collisional Excitation ◽  
Energy Surfaces

The inelastic scattering of PO (X, v = 0) has been investigated by quantum scattering calculations using a new potential energy surface.

Active Learning Accelerates Ab Initio Molecular Dynamics on Pericyclic Reactive Energy Surfaces

2020 ◽  
Author(s):  
Shi Jun Ang ◽  
Wujie Wang ◽  
Daniel Schwalbe-Koda ◽  
Simon Axelrod ◽  
Rafael Gomez-Bombarelli
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Cost ◽  
Reactive Trajectories ◽  
Dynamics Simulations ◽  
Energy Surfaces

<div>Modeling dynamical effects in chemical reactions, such as post-transition state bifurcation, requires <i>ab initio</i> molecular dynamics simulations due to the breakdown of simpler static models like transition state theory. However, these simulations tend to be restricted to lower-accuracy electronic structure methods and scarce sampling because of their high computational cost. Here, we report the use of statistical learning to accelerate reactive molecular dynamics simulations by combining high-throughput ab initio calculations, graph-convolution interatomic potentials and active learning. This pipeline was demonstrated on an ambimodal trispericyclic reaction involving 8,8-dicyanoheptafulvene and 6,6-dimethylfulvene. With a dataset size of approximately</div><div>31,000 M062X/def2-SVP quantum mechanical calculations, the computational cost of exploring the reactive potential energy surface was reduced by an order of magnitude. Thousands of virtually costless picosecond-long reactive trajectories suggest that post-transition state bifurcation plays a minor role for the reaction in vacuum. Furthermore, a transfer-learning strategy effectively upgraded the potential energy surface to higher</div><div>levels of theory ((SMD-)M06-2X/def2-TZVPD in vacuum and three other solvents, as well as the more accurate DLPNO-DSD-PBEP86 D3BJ/def2-TZVPD) using about 10% additional calculations for each surface. Since the larger basis set and the dynamic correlation capture intramolecular non-covalent interactions more accurately, they uncover longer lifetimes for the charge-separated intermediate on the more accurate potential energy surfaces. The character of the intermediate switches from entropic to thermodynamic upon including implicit solvation effects, with lifetimes increasing with solvent polarity. Analysis of 2,000 reactive trajectories on the chloroform PES shows a qualitative agreement with the experimentally-reported periselectivity for this reaction. This overall approach is broadly applicable and opens a door to the study of dynamical effects in larger, previously-intractable reactive systems.</div>

Potential Energy Surfaces

1996 ◽  
Author(s):  
Tomas Baer ◽  
William L. Hase
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electronic State ◽  
Diatomic Molecule ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Electronic States ◽  
Dissociation Energies ◽  
State Potential ◽  
Energy Surfaces

Properties of potential energy surfaces are integral to understanding the dynamics of unimolecular reactions. As discussed in chapter 2, the concept of a potential energy surface arises from the Born-Oppenheimer approximation, which separates electronic motion from vibrational/rotational motion. Potential energy surfaces are calculated by solving Eq. (2.3) in chapter 2 at fixed values for the nuclear coordinates R. Solving this equation gives electronic energies Eie(R) at the configuration R for the different electronic states of the molecule. Combining Eie(R) with the nuclear repulsive potential energy VNN(R) gives the potential energy surface Vi(R) for electronic state i (Hirst, 1985). Each state is identified by its spin angular momentum and orbital symmetry. Since the electronic density between nuclei is different for each electronic state, each state has its own equilibrium geometry, sets of vibrational frequencies, and bond dissociation energies. To illustrate this effect, vibrational frequencies for the ground singlet state (S0) and first excited singlet state (S1) of H2CO are compared in table 3.1. For a diatomic molecule, potential energy surfaces only depend on the internuclear separation, so that a potential energy curve results instead of a surface. Possible potential energy curves for a diatomic molecule are depicted in figure 3.1. Of particular interest in this figure are the different equilibrium bond lengths and dissociation energies for the different electronic states. The lowest potential curve is referred to as the ground electronic state potential. The primary focus of this chapter is the ground electronic state potential energy surface. In the last section potential energy surfaces are considered for excited electronic states. A unimolecular reactant molecule consisting of N atoms has a multidimensional potential energy surface which depends on 3N-6 independent coordinates. For the smallest nondiatomic reactant, a triatomic molecule, the potential energy surface is four-dimensional (three independent coordinates plus the energy). Since it is difficult, if not impossible, to visualize surfaces with more than three dimensions, methods are used to reduce the dimensionality of the problem in portraying surfaces. In a graphical representation of a surface the potential energy is depicted as a function of two coordinates with constraints placed on the remaining 3N-8 coordinates.

Triangulation of the Lowest Energy Sheet for Jahn-Teller Potential Energy Surfaces

1986 ◽  
Vol 41 (3) ◽  
pp. 532-534
Author(s):  
Ariel Fernández
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Potential Energy Surfaces ◽  
Lower Energy ◽  
Energy Surface ◽  
Teller Effect ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Energy Surfaces

The topology of the lower energy sheet for the Potential Energy Surface corresponding to the dynamic Jahn-Teller effect is obtained by means of homological techniques.

Active Learning Accelerates Ab Initio Molecular Dynamics on Pericyclic Reactive Energy Surfaces

2020 ◽  
Author(s):  
Shi Jun Ang ◽  
Wujie Wang ◽  
Daniel Schwalbe-Koda ◽  
Simon Axelrod ◽  
Rafael Gomez-Bombarelli
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Cost ◽  
Reactive Trajectories ◽  
Dynamics Simulations ◽  
Energy Surfaces

<div>Modeling dynamical effects in chemical reactions, such as post-transition state bifurcation, requires <i>ab initio</i> molecular dynamics simulations due to the breakdown of simpler static models like transition state theory. However, these simulations tend to be restricted to lower-accuracy electronic structure methods and scarce sampling because of their high computational cost. Here, we report the use of statistical learning to accelerate reactive molecular dynamics simulations by combining high-throughput ab initio calculations, graph-convolution interatomic potentials and active learning. This pipeline was demonstrated on an ambimodal trispericyclic reaction involving 8,8-dicyanoheptafulvene and 6,6-dimethylfulvene. With a dataset size of approximately</div><div>31,000 M062X/def2-SVP quantum mechanical calculations, the computational cost of exploring the reactive potential energy surface was reduced by an order of magnitude. Thousands of virtually costless picosecond-long reactive trajectories suggest that post-transition state bifurcation plays a minor role for the reaction in vacuum. Furthermore, a transfer-learning strategy effectively upgraded the potential energy surface to higher</div><div>levels of theory ((SMD-)M06-2X/def2-TZVPD in vacuum and three other solvents, as well as the more accurate DLPNO-DSD-PBEP86 D3BJ/def2-TZVPD) using about 10% additional calculations for each surface. Since the larger basis set and the dynamic correlation capture intramolecular non-covalent interactions more accurately, they uncover longer lifetimes for the charge-separated intermediate on the more accurate potential energy surfaces. The character of the intermediate switches from entropic to thermodynamic upon including implicit solvation effects, with lifetimes increasing with solvent polarity. Analysis of 2,000 reactive trajectories on the chloroform PES shows a qualitative agreement with the experimentally-reported periselectivity for this reaction. This overall approach is broadly applicable and opens a door to the study of dynamical effects in larger, previously-intractable reactive systems.</div>

scholarly journals Accurate reproducing kernel-based potential energy surfaces for the triplet ground states of N2O and dynamics for the N + NO ↔ O + N2 and N2 + O → 2N + O reactions

2020 ◽  
Vol 22 (33) ◽  
pp. 18488-18498 ◽  
Author(s):  
Debasish Koner ◽  
Juan Carlos San Vicente Veliz ◽  
Raymond J. Bemish ◽  
Markus Meuwly
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Vibrational Relaxation ◽  
Potential Energy Surfaces ◽  
Reproducing Kernel ◽  
Energy Surface ◽  
Ground States ◽  
Triplet States ◽  
Dynamical Study ◽  
Energy Surfaces

Reproducing kernel-based potential energy surface based on MRCI+Q/aug-cc-pVTZ energies for the triplet states of N2O and quasiclassical dynamical study for the reaction, dissociation and vibrational relaxation.

FISSION POTENTIAL ENERGY SURFACES IN TEN-DIMENSIONAL DEFORMATION SPACE

2009 ◽  
Vol 18 (04) ◽  
pp. 907-913 ◽  
Author(s):  
V. PASHKEVICH ◽  
Y. PYATKOV ◽  
A. UNZHAKOVA
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Correction Method ◽  
Shell Correction ◽  
Deformation Space ◽  
Complete Deformation ◽  
Energy Surfaces ◽  
Cold Fission

Various fission processes are described in terms of high-dimensional potential energy surface in the frame of the Strutinsky shell correction method for actinide region. The complete deformation space is necessary to study the potential energy minima responsible for the cluster radioactivity, cold fission and cold multi-fragmentation valleys. The nuclear shape families for the different fission configurations are obtained without any specific change of the parameters. The coordinate system based on the Cassini ovaloids makes it possible to increase the number of independent deformation parameters without divergence. The higher orders of the deformation are shown to play an important role in the description of the potential energy surface structure.

Mathematical Modeling of the Structures and Bulk Moduli of TX2 Quartz and Cristobalite Structure-Types, T = C,Si,Ge and X = O,S

1988 ◽  
Vol 121 ◽  
Author(s):  
G. V. Gibbs ◽  
M. B. Boisen ◽  
R. T. Downs ◽  
A. C. Lasaga
Keyword(s):  
Mathematical Modeling ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Bulk Modulus ◽  
Small Molecules ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Mo Calculations ◽  
Bending Force ◽  
Energy Surfaces

ABSTRACTModels of the oxide and sulfide structure-types of quartz and cristobalite have been made using potential energy surfaces derived from MO calculations on small molecules. The bond length and angle and the volume compressibility data calculated for quartz match those observed for pressures up to 40 kbars. An analysis of the force constants that define the potential energy surface indicates that the bulk modulus of the mineral is governed primarily by the bending force constant of the bridging angle. Similar calculations were completed for the GeO2 form of quartz, but the agreement with the observed data is somewhat poorer. A modeling of the CO2 form of quartz predicts that it would be significantly harder, more incompressible and show less expansibility than the SiO2 form.

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