COMPARATIVE STUDY OF REACTION RATE CONSTANTS FOR THE NH3 + H → NH2 + H2 REACTION WITH GLOBE DYNAMICS AND TRANSITION STATE THEORIES

2009 ◽  
Vol 08 (06) ◽  
pp. 1227-1233 ◽  
Author(s):  
JU LIPING ◽  
LU RUIFENG
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Rate Constants ◽  
Quantum Dynamics ◽  
Classical Trajectory ◽  
State Theory ◽  
Title Reaction ◽  
Reaction Rate Constants ◽  
Barrier Type ◽  
Good Agreement

The nine-dimension quasi-classical trajectory (QCT) calculations have been carried out for the title reaction with a global potential energy surface (PES) constructed by Corchado and Espinosa-García (J Chem Phys106:4013, 1997). The detailed dynamics calculations cover the specific collision energies falling in the range of 0.62–3.04 eV, which are sufficient to fit the calculated reactive cross-sections into a barrier-type excitation function and to obtain the thermal rate constants. The present QCT rate constants are in good agreement with the recent quantum dynamics (QD) results, both of which are much lower than that of the previous variational transition state theory (VTST).

EFFECTS OF ROTATIONAL AND VIBRATIONAL EXCITATION ON THE STEREODYNAMICS OF THE O (D-1) + HCl → OH + Cl REACTION

2009 ◽  
Vol 08 (06) ◽  
pp. 1177-1184 ◽  
Author(s):  
QIANG WEI ◽  
VICTOR WEI-KEH WU ◽  
BO ZHOU
Keyword(s):  
Cross Sections ◽  
Collision Energy ◽  
Energy Surface ◽  
Vibrational Excitation ◽  
Classical Trajectory ◽  
Rotational Excitation ◽  
Title Reaction ◽  
Vibrational Excitations ◽  
Product Vector ◽  
Good Agreement

The stereodynamics of the title reaction on the ground 1 1A′ potential energy surface (PES) has been studied using quasi-classical trajectory (QCT) method. Collision energy of 6.4 kcal/mol is considered, and vector properties including angular momentum alignment distributions and polarization-dependent differential cross-sections (PDDCS) of the product OH are presented. Furthermore, the influence of reagent rotational excitation and vibrational excitation on the product vector properties has also been studied in the present work. The results indicate that the distribution of the P(θr) and P(ϕr) are sensitively affected by the rotational and vibrational excitation. The rotational excitation decreases the degree of alignment and orientation, while vibrational excitation increases the degree of alignment and orientation. The PDDCS (2π/σ)(dσ20/dωt) and (2π/σ)(dσ22+/dωt) are sensitively influenced by rotational and vibrational excitations, while the PDDCS ((2π/σ)(dσ00/dωt)) and (2π/σ)(dσ21-/dωt) are not. The preference of forward scattering has been found from the results of PDDCS ((2π/σ)(dσ00/dωt)), which is in good agreement with the experimental results.

Reaction Rate Constants from Classical Trajectories of Atom-Diatomic Molecule Collisions

2008 ◽  
Vol 63 (3-4) ◽  
pp. 159-169
Author(s):  
Hamzeh M. Abdel-Halim ◽  
Sawsan M. Jaafreh
Keyword(s):  
Cross Sections ◽  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Diatomic Molecules ◽  
Equations Of Motion ◽  
Strong Dependence ◽  
Three Dimensional ◽  
Reaction Rates ◽  
Classical Trajectory ◽  
Reaction Rate Constants

Classical trajectory calculations for various atom-diatomic molecules were preformed using the three-dimensional Monte Carlo method. The reaction probabilities, cross-sections and rate constants of several systems were calculated. Equations of motion, which predict the positions and momenta of the colliding particles after each step, have been integrated numerically by the Runge-Kutta-Gill and Adams-Moulton methods. Morse potential energy surfaces were used to describe the interaction between the atom and each atom in the diatomic molecules. The results were compared with experimental ones and with other theoretical values. Good agreement was obtained between calculated rate constants and those obtained experimentally. Also, reasonable agreement was observed with theoretical rate constants obtained by other investigators using different calculation methods. The effects of the temperature, the nature of the colliding particles and the thermochemistry were studied. The results showed a strong dependence of the reaction rates on these factors.

Quasi-Classical Trajectory Study of the Scalar Properties of the Reaction N(4S)+H2(v=0,1,2,3; j=0)→NH+H

2014 ◽  
Vol 924 ◽  
pp. 227-232
Author(s):  
Yong Jiang Yu ◽  
Xiao Yue Yu
Keyword(s):  
Cross Sections ◽  
Chem Phys ◽  
Classical Trajectory ◽  
Reaction Cross ◽  
Vibrational States ◽  
Rotational States ◽  
Reaction Rate Constants ◽  
Internuclear Distances ◽  
Scalar Properties ◽  
Good Agreement

Quasi-classical trajectory dynamical calculations of the title reactions have been performed on an accurate NH2 potential energy surface [Poveda LA, Varandas AJC, Phys Chem Chem Phys 7:2867,2005] over the collision energy range of 25-80 kcal mol-1. The reaction cross sections, variation of internuclear distances of N-Ha, N-Hb and Ha-Hb, and the reaction rate constants are reported for various initial vibrational and rotational states of H2 (v=0-3; j=0) molecules. The reaction cross section in the ground vibrational state of H2 and the rate constant over the thermal distribution of initial vibrational states of H2 are compared with other theoretical results and existing experimental results in the literature, showing good agreement.

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