scholarly journals Interpolation and Extrapolation of Global Potential Energy Surfaces for Polyatomic Systems by Gaussian Processes with Composite Kernels

2020 ◽  
Vol 16 (3) ◽  
pp. 1386-1395 ◽  
Author(s):  
J. Dai ◽  
R. V. Krems
Keyword(s):  
Potential Energy ◽  
Gaussian Processes ◽  
Potential Energy Surfaces ◽  
Polyatomic Systems ◽  
Energy Surfaces

scholarly journals Representing Global Reactive Potential Energy Surfaces Using Gaussian Processes

2017 ◽  
Vol 121 (13) ◽  
pp. 2552-2557 ◽  
Author(s):  
Brian Kolb ◽  
Paul Marshall ◽  
Bin Zhao ◽  
Bin Jiang ◽  
Hua Guo
Keyword(s):  
Potential Energy ◽  
Gaussian Processes ◽  
Potential Energy Surfaces ◽  
Reactive Potential ◽  
Energy Surfaces

scholarly journals Constructing Potential Energy Surfaces for Polyatomic Systems: Recent Progress and New Problems

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
J. Espinosa-Garcia ◽  
M. Monge-Palacios ◽  
J. C. Corchado
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Hydrogen Abstraction ◽  
Molecular Size ◽  
General Applicability ◽  
Advantages And Disadvantages ◽  
Kinetics And Dynamics ◽  
Functional Forms ◽  
Polyatomic Systems ◽  
Energy Surfaces

Different methods of constructing potential energy surfaces in polyatomic systems are reviewed, with the emphasis put on fitting, interpolation, and analytical (defined by functional forms) approaches, based on quantum chemistry electronic structure calculations. The different approaches are reviewed first, followed by a comparison using the benchmark H + CH4 and the H + NH3 gas-phase hydrogen abstraction reactions. Different kinetics and dynamics properties are analyzed for these reactions and compared with the available experimental data, which permits one to estimate the advantages and disadvantages of each method. Finally, we analyze different problems with increasing difficulty in the potential energy construction: spin-orbit coupling, molecular size, and more complicated reactions with several maxima and minima, which test the soundness and general applicability of each method. We conclude that, although the field of small systems, typically atom-diatom, is mature, there still remains much work to be done in the field of polyatomic systems.

More complex systems

2003 ◽  
Keyword(s):  
Energy Transfer ◽  
Potential Energy ◽  
Complex Systems ◽  
Chemical Reactions ◽  
Potential Energy Surfaces ◽  
Electronic States ◽  
Polyatomic Molecules ◽  
Polyatomic Systems ◽  
Energy Surfaces ◽  
Semi Empirical

By more complex systems we mean systems containing on the order of hundreds or thousands of atoms, or molecules with less atoms but with “complicated” motions, the latter being the case when considering collisions between polyatomic molecules. In the present chapter we deal with quantum-classical methods for treating energy transfer in collisions involving polyatomic molecules, molecule surface scattering, reactions in polyatomic systems and solution. We will assume that it is possible to construct realistical potential energy surfaces for the systems. Obviously, these surfaces will be of empirical or semi-empirical nature. In some of the methods, as for instance the reaction path method, one tries to minimize the information needed on potential energy surfaces. Chemical reactions and energy transfer processes in the gas phase are often studied using just a single adiabatic Born-Oppenheimer potential energy surface. However non-adiabatic effects, that is, coupling between different electronic states, is an important aspect in chemistry. If the coupling between the various electronic states can be neglected, the “electronic” effect reduces to that of a statistical degeneracy factor ge [180].

Resolving the Quadruple Bonding Conundrum in C2 Using Insights Derived from Excited State Potential Energy Surfaces: A Molecular Orbital Perspective

2019 ◽  
Author(s):  
Ishita Bhattacharjee ◽  
Debashree Ghosh ◽  
Ankan Paul
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Molecular Orbital ◽  
High Spin ◽  
Potential Energy Surfaces ◽  
Valence Bond ◽  
Deep Minimum ◽  
State Potential ◽  
Energy Surfaces ◽  
Mo Theory

The question of quadruple bonding in C<sub>2</sub> has emerged as a hot button issue, with opinions sharply divided between the practitioners of Valence Bond (VB) and Molecular Orbital (MO) theory. Here, we have systematically studied the Potential Energy Curves (PECs) of low lying high spin sigma states of C<sub>2</sub>, N<sub>2</sub> and Be<sub>2</sub> and HC≡CH using several MO based techniques such as CASSCF, RASSCF and MRCI. The analyses of the PECs for the<sup> 2S+1</sup>Σ<sub>g/u</sub> (with 2S+1=1,3,5,7,9) states of C<sub>2</sub> and comparisons with those of relevant dimers and the respective wavefunctions were conducted. We contend that unlike in the case of N<sub>2</sub> and HC≡CH, the presence of a deep minimum in the <sup>7</sup>Σ state of C<sub>2</sub> and CN<sup>+</sup> suggest a latent quadruple bonding nature in these two dimers. Hence, we have struck a reconciliatory note between the MO and VB approaches. The evidence provided by us can be experimentally verified, thus providing the window so that the narrative can move beyond theoretical conjectures.

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