scholarly journals Quantum Instanton Evaluations of the Thermal Rate Constants for Complex Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Yi Zhao ◽  
Wenji Wang
Keyword(s):  
Partition Function ◽  
Complex Systems ◽  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
Quantum Effect ◽  
Theoretical Data ◽  
Reaction Rate Constants ◽  
Energy Surfaces ◽  
Quantum Instanton

Quantum instanton (QI) approximation is recently proposed for the evaluations of the chemical reaction rate constants with use of full dimensional potential energy surfaces. Its strategy is to use the instanton mechanism and to approximate time-dependent quantum dynamics to the imaginary time propagation of the quantities of partition function. It thus incorporates the properties of the instanton idea and the quantum effect of partition function and can be applied to chemical reactions of complex systems. In this paper, we present the QI approach and its applications to several complex systems mainly done by us. The concrete systems include, (1) the reaction of H+CH4→H2+CH3, (2) the reaction of H+SiH4→H2+SiH3, (3) H diffusion on Ni(100) surface; and (4) surface-subsurface transport and interior migration for H/Ni. Available experimental and other theoretical data are also presented for the purpose of comparison.

Progress towards machine learning reaction rate constants

2021 ◽  
Author(s):  
Evan Komp ◽  
Nida Janulaitis ◽  
Stephanie Valleau
Keyword(s):  
Machine Learning ◽  
Potential Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Reaction Rate Constants ◽  
The Cost ◽  
Energy Surfaces

Quantum and classical reaction rate constant calculations come at the cost of exploring potential energy surfaces. Due to the “curse of dimensionality”, their evaluation quickly becomes unfeasible as the system...

Exact state-to-state quantum dynamics of the F+HD→HF(v′=2)+D reaction on model potential energy surfaces

2008 ◽  
Vol 129 (6) ◽  
pp. 064303 ◽  
Author(s):  
Dario De Fazio ◽  
Vincenzo Aquilanti ◽  
Simonetta Cavalli ◽  
Antonio Aguilar ◽  
Josep M. Lucas
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
Model Potential ◽  
Energy Surfaces

CHEMICAL REACTIONS IN THE O(1D) + HCl SYSTEM III.

2002 ◽  
Vol 01 (02) ◽  
pp. 285-293 ◽  
Author(s):  
HIDEYUKI KAMISAKA ◽  
HIROKI NAKAMURA ◽  
SHINKOH NANBU ◽  
MUTSUMI AOYAGI ◽  
WENSHENG BIAN ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Potential Energy ◽  
Chemical Reactions ◽  
Reaction Mechanisms ◽  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
Total Angular Momentum ◽  
Nonadiabatic Transitions ◽  
Angular Momentum Quantum Number ◽  
Energy Surfaces

Using the accurate global potential energy surfaces for the 11A′′ and 21A′ states reported in the previous sister Paper I, detailed quantum dynamics calculations are performed for these adiabatic surfaces separately for J = 0 (J: total angular momentum quantum number). In addition to the significant overall contributions of these states to the title reactions reported in the second Paper II of this series, quantum dynamics on these excited potential energy surfaces (PES) are clarified in terms of the PES topographies, which are quite different from that of the ground PES. The reaction mechanisms are found to be strongly selective and nicely explained as vibrationally nonadiabatic transitions in the vicinity of potential ridge.

Theoretical study on the chemical formation mechanism of a β-myrcene ozonolysis reaction under atmospheric conditions

2012 ◽  
Vol 90 (8) ◽  
pp. 708-715 ◽  
Author(s):  
Yuyang Zhao ◽  
Jing Bai ◽  
Chenxi Zhang ◽  
Chen Gong ◽  
Xiaomin Sun
Keyword(s):  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Single Point ◽  
State Theory ◽  
Tunneling Effect ◽  
Atmospheric Conditions ◽  
Functional Theory ◽  
Real Atmosphere ◽  
Energy Surfaces

Density functional theory (DFT) was used to study the β-myrcene ozonolysis reaction. The reactants, intermediates, transition states, and products were optimized at the MPWB1K/6–31G(d,p) level. The single-point energies were performed at the MPWB1K/6–311+G(3df,2p) level. The profiles of the potential energy surfaces were constructed and the rate constants of the reaction steps were analyzed. The possible reaction mechanisms for the ozonolysis intermediates in real atmosphere are also discussed. Based on quantum chemistry information, the rate constants were calculated using Rice–Ramsperger–Kassel–Marcus (RRKM) theory and the canonical variational transition-state theory (CVT) with small curvature tunneling effect (SCT). Arrhenius equations of rate constants over the temperature range of 200–800 K are provided, and the lifetimes of the reaction species in the troposphere were estimated according to rate constants.

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