H + H2 quantum dynamics using potential energy surfaces based on the XYG3 type of doubly hybrid density functionals: validation of the density functionals.

The potential energy surfaces for the H + H2 exchange reaction are determined, using the standard Becke-3_parameter-Lee-Yang-Parr (B3LYP) hybrid exchange-correlation functional and the recently developed XYG3 type (xDH) doubly hybrid functionals. Quantum dynamical results calculated on these density functional theory surfaces revealed that the accuracy for the surfaces from the xDH functionals is quite satisfactory as compared to the benchmark Boothroyd-Keogh-Martin-Peterson-2 surface, whereas B3LYP is wholly inadequate in describing this simplest reaction despite the fact that it has been widely used to study reactions in complex systems. It is shown that further improvements can be achieved if the xDH functional parameters are fine-tuned to be reaction specific.