The relativistic Dirac-Coulomb-Fock effect on atomization energies

We have used a second-order perturbation treatment of the Dirac-Coulomb-Har tree-Fock method to estimate relativistic contributions to energies in the G2/97 test set. The one-electron relativistic effect on atomization energie s of molecules containing first-and second-row atoms nearly always reduces binding. When the relativistic corrections are included in G3 theory and as sessed on the G2/97 test set, there is little change in overall performance . (C) 1999 American Institute of Physics. [S0021-9606(99)30815-1].