Ab initio path integral ring polymer molecular dynamics: Vibrational spectra of molecules

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

Download Full-text

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

10.26434/chemrxiv.14650326 ◽

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>

Download Full-text

Investigating Tunneling-Controlled Chemical Reactions through Ab Initio Ring Polymer Molecular Dynamics

The Journal of Physical Chemistry Letters ◽

10.1021/acs.jpclett.1c01630 ◽

2021 ◽

pp. 6714-6721

Author(s):

Xinyang Li ◽

Pengfei Huo

Keyword(s):

Molecular Dynamics ◽

Ab Initio ◽

Chemical Reactions ◽

Ring Polymer ◽

Ring Polymer Molecular Dynamics

Download Full-text

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

10.26434/chemrxiv.14650326.v1 ◽

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>

Download Full-text