Scalar relativistic effects on energies of molecules containing atoms fromhydrogen through argon

Stationary direct perturbation theory is used to calculate a scalar relativ istic correction to the species in the G3/99 test set. We observe that the relativistic energy almost always reduces atomization energies, electron af finities, and ionization potentials. Exceptions occur when s orbitals play a predominant role in the energy differences between reactants and products . The scalar relativistic energy, when added to G3 theory and the empirical parameters are reoptimized, gives slightly worse agreement with experiment . (C) 2001 American Institute of Physics.