A schematic of vibrational paths away from the reaction surface (for clarity this diagram uses and so the surface is just the MEP). The black line represents the MEP while the red and blue lines represent different harmonic curves with the same geometry at their minima but different geometries away from . The view on the right is looking down on the MEP from above and highlights the curved path followed by the red line relative to the straight line motion of the blue vibration. The coincidence of the two vibrations on the MEP indicates that all points on the red and blue paths correspond to the same MEP geometry. As the geometries permitted by harmonic expansion are determined by the coordinate frame it is clear that this is equivalent to the definition of for points away from the MEP.
Schematic representation of the system.
: the difference between the ZPEs of the spectator modes calculated with curvilinear and rectilinear projection. The energy difference, in Hartree, is plotted for a number of values of and across the reaction surface. Points in red are for and points in blue are for . The translucent plane is set at as a guide to the eye.
Thermal rate constants for reaction (R1). The experimental data are taken from Ref. 22.
Thermal rate constants for reaction (R1) compared with results from experiments and previous theoretical studies (references given in the text).
Thermal rate constants for reaction (R2) compared with results from experiments and previous theoretical studies (references given in the text).
Geometries of the asymptotic species and TS [the same for (R1) and (R2)], optimized at MP2/cc-pVTZ. Angles are in degrees and distances in . is the incoming H atom in (R1) and is the abstracted H atom in that reaction. The TS has symmetry.
Single point CCSDT(T)/cc-pVTZ//MP2/cc-pVTZ energies.
Parameters defining potential energy surfaces including spectator mode ZPE corrections evaluated via projection in curvilinear and rectilinear coordinates.
Frequencies in for the TS and all relevant asymptotic species, calculated at MP2/cc-pVTZ (parentheses indicate multiplicities).
Spectator mode frequencies for the reaction surface geometry corresponding to and . Frequencies are quoted after projection in both rectilinear and curvilinear coordinates (see text). The frequencies are listed in order of increasing absolute value.
Thermal rate constants (in ) for reaction (R1) evaluated on a PES adiabatically corrected with spectator mode ZPEs: indicates curvilinear projection and indicates rectilinear projection.
Thermal rate constants (in ) for reaction (R2) evaluated on a PES adiabatically corrected with spectator mode ZPEs: indicates curvilinear projection and indicates rectilinear projection.
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