Hartree–Fock perturbative corrections for total and reaction energies

We have performed an assessment of the Hartree-Fock perturbative correction (HFPC) on a large and diverse set of molecules and reactions. Errors in both absolute and reaction energies with respect to converged secondary basis Hartree-Fock results are reported for a wide spectrum of primary/secondary basis set combinations. These results show that using an adequate primary basis, HFPC can accurately reproduce secondary basis energies at a substantially reduced cost. Comparisons of HFPC with the related dual basis Hartree-Fock (DBHF) scheme are also made for several molecules and target secondary basis sets. Our results indicate that HFPC is faster and more accurate than DBHF for approaching triple-zeta basis sets. For quadruple-zeta secondary basis sets, HFPC is capable of yielding more accurate energies at a marginally increased cost over DBHF.