An integrated molecular orbital + molecular orbital (IMOMO) study of the O + H-R → OH + R• reaction class

We investigate the O + H-R → OH + R• reaction class by employing the integrated molecular orbital + molecular orbital (IMOMO) methodology. The QCISD(T), MP4, and MP2 methods are employed as the high-level theories in the IMOMO method based on the geometries optimized at the BH&HLYP and MPW1K methods. The results show that the energies predicted from both QCISD(T) and MP4 calculations can reasonably be reproduced by the IMOMO method. In particular, the IMOMO method yields the mean absolute deviation of about 1 kcal/mol in reaction energies and less than 0.4 kcal/mol in classical barrier heights. The predicted thermal rate constants are in good agreement with the available experimental data. This approach has been further proven to be powerful tools for studying reactions involving large molecular systems.