Figure 2. Optimized structures with atom numbering and relative energies (kcal mol-1; in parenthesis, ZPE-corrected values) for the most important stationary points for the gas-phase reaction HN+CH + HCOOH¢ªHN+-CH2-COOH (2) computed at the B3LYP/6-31++G(d,p) level of theory (RC3 geometry was obtained with the 6-31G(d) basis set).