Kinetic study of the OH + HO2 → H2O + O2 reaction using ring polymer molecular dynamics and quantum dynamics

2020 ◽  
Vol 22 (41) ◽  
pp. 23657-23664
Author(s):  
Yang Liu ◽  
Hongwei Song ◽  
Jun Li
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Kinetic Study ◽  
Quantum Dynamics ◽  
Energy Surface ◽  
Title Reaction ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Kinetics Of

The kinetics of the title reaction is studied by running the ring polymer molecular dynamics and quantum dynamics on an accurate potential energy surface.

Dynamics and kinetics of the Si(1D) + H2/D2 reactions on a new global ab initio potential energy surface

2021 ◽  
Vol 23 (10) ◽  
pp. 6141-6153
Author(s):  
Jianwei Cao ◽  
Yanan Wu ◽  
Haitao Ma ◽  
Zhitao Shen ◽  
Wensheng Bian
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Quantum Dynamics ◽  
Energy Surface ◽  
Molecular Dynamics Calculations ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Kinetics Of

Quantum dynamics and ring polymer molecular dynamics calculations reveal interesting dynamical and kinetic behaviors of an endothermic complex-forming reaction.

An accurate potential energy surface and ring polymer molecular dynamics study of the Cl + CH4 → HCl + CH3 reaction

2020 ◽  
Vol 22 (1) ◽  
pp. 344-353 ◽  
Author(s):  
Yang Liu ◽  
Jun Li
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Entrance Channel ◽  
Rate Coefficients ◽  
Spin Orbit ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics

Thermal rate coefficients for the Cl + CH4/CD4 reactions were studied on a new full-dimensional accurate potential energy surface with the spin–orbit corrections considered in the entrance channel.

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>

Theoretical study of the Cl(2P) + SiH4 reaction: Global potential energy surface and product pair-correlated distributions. Comparison with experiment.

2021 ◽  
Author(s):  
J. Espinosa-Garcia ◽  
Jose Carlos Corchado
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Theoretical Study ◽  
Title Reaction ◽  
Comparison With Experiment ◽  
Explicitly Correlated ◽  
High Level ◽  
First Time ◽  
Product Pair

For the theoretical study of the title reaction, an analytical full-dimensional potential energy surface named PES-2021 was developed for the first time, by fitting high-level explicitly-correlated ab initio data. This...

scholarly journals On-the-Fly Ring-Polymer Molecular Dynamics Calculations of the Dissociative Photodetachment Process of the Oxalate Anion

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7250
Author(s):  
Yukinobu Takahashi ◽  
Yu Hashimoto ◽  
Kohei Saito ◽  
Toshiyuki Takayanagi
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Quantum Effects ◽  
Experimental Spectrum ◽  
Computational Time ◽  
Oxalate Anion ◽  
Dissociative Photodetachment ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Nuclear Quantum Effects

The dissociative photodetachment dynamics of the oxalate anion, C2O4H− + hν → CO2 + HOCO + e−, were theoretically studied using the on-the-fly path-integral and ring-polymer molecular dynamics methods, which can account for nuclear quantum effects at the density-functional theory level in order to compare with the recent experimental study using photoelectron–photofragment coincidence spectroscopy. To reduce computational time, the force acting on each bead of ring-polymer was approximately calculated from the first and second derivatives of the potential energy at the centroid position of the nuclei beads. We find that the calculated photoelectron spectrum qualitatively reproduces the experimental spectrum and that nuclear quantum effects are playing a role in determining spectral widths. The calculated coincidence spectrum is found to reasonably reproduce the experimental spectrum, indicating that a relatively large energy is partitioned into the relative kinetic energy between the CO2 and HOCO fragments. This is because photodetachment of the parent anion leads to Franck–Condon transition to the repulsive region of the neutral potential energy surface. We also find that the dissociation dynamics are slightly different between the two isomers of the C2O4H− anion with closed- and open-form structures.

scholarly journals Investigating Tunneling Controlled Chemical Reactions Through Ab-Initio Ring Polymer Molecular Dynamics

2021 ◽  
Author(s):  
Xinyang Li ◽  
Pengfei Huo
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Chemical Reaction ◽  
Quantum Tunneling ◽  
Quantum Dynamics ◽  
Density Functional ◽  
Molecular System ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Dynamics Simulations

<div>We use the ab-initio ring polymer molecular dynamics (RPMD) approach to investigate tunneling controlled reactions in methylhydroxycarbene. Nuclear tunneling effects enable molecules to overcome the barriers which can not be overcome classically. Under low-temperature conditions, intrinsic quantum tunneling effects canfacilitate the chemical reaction in a pathway that is neither favored thermodynamically nor kinetically. This</div><div>behavior is referred to as the tunneling controlled chemical reaction and regarded as the third paradigm of chemical</div><div>reaction controls. In this work, we use the ab-initio RPMD approach to incorporate the tunneling effects in our quantum dynamics simulations. The reaction kinetics of two competitive reaction pathways at various temperatures are investigated with the Kohn-Sham density functional theory (KS-DFT) on-the-fly molecular dynamics simulations and the ring polymer quantization of the nuclei. The reaction rate constants obtained here agree extremely well with the experimentally measured rates. We demonstrate the feasibility of using ab-initio RPMD rate calculations in a realistic molecular system, and provide an interesting and important example for future investigations on reaction mechanisms dominated by quantum tunneling effects.</div>

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