Dual-level reaction-path dynamics (the III approach to VTST with semiclassical tunneling). Application to OH + NH[sub 3] [yields] H[sub 2]O + NH[sub 2]

Journal Article · Wed Jan 11 23:00:00 EST 1995 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100002a037· OSTI ID:6582737

Corchado, J C; Espinosa-Garcia, J ^[1]; Hu, W P; Rossi, I; Truhlar, D G ^[2]

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1. Universidad de Extremadura, Badajoz (Spain)
2. Univ. of Minnesota, Minneapolis, MN (United States)

We consider a new approach to reaction-path dynamics calculations in which the reaction path is calculated at a low level (LL) of theory and stationary point information from a high level (HL) of theory is used to interpolate corrections to energetic quantities, vibrational frequencies, and moments of inertia. Such a calculation is labeled XII/Y, where X denotes the high level and Y the low level. The theory is applied to the reaction OH + NH[sub 3] and three isotopomeric analogs. The highest-level optimization reported for the saddle point is QCISD(T)//MP2/aug-cc-pVTZ, which yields a classical barrier height of 3.65 kcal/mol. The rate constant is calculated at two levels, QCISD(T)//MP2/aug-cc-p VTZ[MP2/aug-cc-p VDZ] ///MP2/6-31G** and QCISD(T)//MP2/aug-cc-pVTZ[MP2/aug-cc-pVDZ] ///PM3-SRP; the calculated rare constant for the unsubstituted reaction is approximately invariant to the low level used in the dual-level scheme and agrees with experiment within a factor of 1.13 at 250 K and within a factor of 1.14 at 1500 K. 79 refs., 4 figs., 13 tabs.

• OSTI ID: 6582737
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 99:2; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400800 -- Combustion
Pyrolysis
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99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
AMMONIA
CALCULATION METHODS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION
COMBUSTION KINETICS
DATA
DYNAMICS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROXYL RADICALS
INFORMATION
KINETICS
MECHANICS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NUMERICAL DATA
OXIDATION
RADICALS
REACTION KINETICS
THEORETICAL DATA
THERMOCHEMICAL PROCESSES