Classical trajectory study of CD2OH+→CDO++HD on potential energy surfaces constructed at various quantum chemical levels:: Scaling of product mode-specific energies

Potential energy surfaces for the title reaction have been constructed by interpolation of 40 local potentials along the intrinsic reaction coordinate obtained by quantum chemical calculations at the semiempirical, Hartree-Fock (HF), post-HF, and density functional thoery (DFT) levels of theory. Classical trajectory calculations have been carried out and the average product mode-specific energies originating from the reverse barriers have been estimated. When normalized to the reverse barrier heights, the mode-specific energies evaluated at the HF, post-HF and theory DFT levels have been found to be comparable, indicating that the energy partitioning data are scaled to the barrier heights at these levels of theory. Namely, dynamical results obtained on potential energy surfaces constructed at moderate quantum chemical levels were similar (within similar to 5%) to those at higher levels. It has been found theoretically that classical dynamics on two potential energy surfaces related by simple scaling results in scaled mode-specific energies. As a guideline for general cases, the similarity factor between two potential energy surfaces has been defined, which shows a good correlation with the scalability of the energy partitioning data. (C) 1999 American Institute of Physics. [S0021-9606(99)00602-9].