The barrier height of the F+H2 reaction revisited: Coupled-cluster and multireference configuration-interaction benchmark calculations

Abstract

Large scale coupled-cluster benchmark calculations have been carried out to determine the barrier height of the F+ H2 reaction as accurately as possible. The best estimates for the barrier height of the linear and bent transition states amount to 2.16 and 1.63 kcalmol, respectively. These values include corrections for core correlation, scalar-relativistic effects, spin-orbit effects, as well as the diagonal Born-Oppenheimer correction. The CCSD(T) basis-set limits are estimated using extrapolation techniques with augmented quintuple and sextuple-zeta basis sets, and remaining N -electron errors are determined using coupled-cluster singles, doubles, triples, quadruples calculations with up to augmented quintuple-zeta basis sets. The remaining uncertainty is estimated to be less than 0.1 kcalmol. The coupled-cluster results are used to calibrate multireference configuration-interaction calculations with empirical scaling of the correlation energy. © 2008 American Institute of Physics.