Calculated Infrared Frequencies and Intensities of the HO2 Radical

A systematic study of basis set and correlation effects on the harmonic frequencies and infrared intensities of the H02 radical has been conducted. Correlation consistent basis sets were employed at the SCF, MBPT2 through MBPT4, and CCSD levels of theory. The basis set effects yield the anticipated trends for the geometries and harmonic frequencies. The basis set effects yield the anticipated trends for the for H02. Even at the CCSD level with the largest basis set used aug-cc-pVTZ, the intensities are 36.2 I sub 1, 41.9 I sub 2, and 32.2 kmmol I sub 3, overestimating the experimental values by factors of 8.0,3.2, and 4.1, respectively. Comparison with previous work on H02 and a discussion of the predictive ability for these methods are made.