A re-examination of the heat of formation of HO₂ using ab initio molecular orbital theory

The heat of formation of HO2 radical has been estimated in a spin-conserved reaction scheme with energies calculated at QCISD(T)/6-311 + G(2df,p)//QCISD(T)/6-311G(d,p) level of theory. The result, ΔH o f(HO2, 298 K) = 21.4 ± 4.2 kJ mol-1, supports the most recent experimental value of 15.9 ± 5.0 kJ mol-1, and thus resolves the discrepancy in the heat of formation of this radical.