Monte Carlo trajectory and master equation simulation of the nonequilibrium dissociation rate coefficient for Ar+H/sub 2/. -->. Ar+2H at 4500 K

Journal Article · Sun Mar 01 04:00:00 EST 1987 · J. Chem. Phys.; (United States)

OSTI ID:6875155

Haug, K; Truhlar, D G; Blais, N C

Thermally averaged rate coefficients for state-to-state rovibrational transitions and dissociation from individual states in Ar+para-H/sub 2/ collisions at 4500 K are derived from Monte Carlo quasiclassical trajectory calculations. The problem of multidimensional interpolation of state-to-state rate constants is discussed, and the rate matrix is completed by nonlinear least-squares fitting. The relaxation time, the induction time, and the steady dissociation rate are calculated by a matrix eigenvalue solution of the master equation simulating a shock wave experiment on para-H/sub 2/ dilute in Ar. Rotational--vibrational nonequilibrium effects are fully included. We have found that multiquantum transitions play a very significant role in determining the observable dissociation rate and that the master equation eigenmodes representing internal energy redistribution are little affected by the reaction process. The final steady dissociation rate is 2.8 times less than at local equilibrium. Various lumping schemes are tested, and we show that the original 162-state system can be well approximated by a 10-state model which predicts a factor of 2.4 for the nonequilibrium effect. However, we are unable to find equally successful models involving smaller numbers of states, and the popular vibrational ladder model and the corresponding rotational ladder model do not reproduce the full results even qualitatively.

• Research Organization: Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
• OSTI ID: 6875155
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 86:5; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ARGON
CHEMICAL REACTION KINETICS
COMPUTERIZED SIMULATION
DISSOCIATION
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
GASES
HYDROGEN
KINETICS
MONTE CARLO METHOD
NONMETALS
RARE GASES
REACTION KINETICS
ROTATIONAL STATES
SIMULATION
VERY HIGH TEMPERATURE
VIBRATIONAL STATES