Kinetic isotope effects: Theoretical prediction of the thermal rate coefficient for the reaction D+O/sub 2/. -->. OD+O

Journal Article · Tue Dec 01 04:00:00 EST 1981 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.441978· OSTI ID:6087621

Miller, J A

Quasiclassical trajectory (QCT) and quasiclassical trajectory quantum mechanical threshold (QCT--QMT) calculations are reported for the reaction D+O/sub 2/..-->..OD+O. The thermal rate coefficient from the QCT--QMT analysis was determined to be k/sub 2/ = 8.12 x 10/sup 15/T/sup -0.659/ exp(-15 041/RT) cm/sup 3//mol s, for 250..OH+O, the ratio k/sub 2//k/sub 1/ is found to vary from 7.5 at 250 K to 0.8 at 2500 K. The primary isotope effects controlling this difference are the difference in zero-point vibrational energies of the product diatoms at low temperature and the difference in reactant collision frequencies at high temperature. In addition the calculations show slightly less negative Arrhenius curvature (n/sub 2/ = -0.659, n/sub 1/ = -0.816) for R2 than for R1, an effect anticipated from the previous analysis. However, the magnitude of the difference between n/sub 1/ and n/sub 2/ is approximately the same as estimates of the maximum uncertainty in the calculations themselves. It is concluded that a factor of 2 in the mass of the attacking atom is not sufficient to distinguish accurately differences in Arrhenius curvature arising from the L+HH mass combination of the reactants, either theoretically or experimentally.

• Research Organization: Combustion Physics Division, Sandia National Laboratories, Livermore, California 94550
• OSTI ID: 6087621
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 75:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
CHEMICAL REACTION KINETICS
DEUTERIUM
ELEMENTS
HIGH TEMPERATURE
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
MEDIUM TEMPERATURE
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OXYGEN
REACTION KINETICS
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
VERY HIGH TEMPERATURE