INCLUSION OF EXACT EXCHANGE FOR SELF-INTERACTION-CORRECTED H-3 DENSITY-FUNCTIONAL POTENTIAL-ENERGY SURFACE

The effect of the inclusion of the exact exchange into self-interactio n corrected generalized gradient approximation density functional theo ry (GGA-DFT) for the simplest hydrogen abstraction reaction, H + (H)2 --> H-3 --> H-2 + H, is presented using a triple-zeta augmented 6-311+G(d,3pd) basis set. The introduction of the self-interaction correcti on has a considerably larger effect on molecular geometry and vibratio nal frequencies than the inclusion of the exact exchange. We investiga te the influence of the self-interaction error on the shape of the pot ential energy surface around the transition state of the hydrogen abst raction reaction. The decomposition of the self-interaction error into correlation and exchange parts shows that the exchange self-interacti on error is the main component of the energy barrier error. The best a greements with the experimental barrier height were achieved by self-i nteraction corrected B3LYP, B-LYP and B3PW functionals with errors of 1.5, 2.9 and 3.0 kcal/mol, respectively.